feat(scep): SCEP probe in network scanner for fleet-readiness assessment

Phase 11.5 of the SCEP RFC 8894 + Intune master bundle. Adds an
operator-facing SCEP probe that issues GetCACaps + GetCACert against
an arbitrary SCEP server URL and returns a structured posture snapshot
(reachable + advertised caps + RFC 8894 / AES / POST / Renewal /
SHA-256 / SHA-512 support flags + CA cert subject + issuer + NotBefore
+ NotAfter + days-to-expiry + algorithm + chain length).

Two operator use cases per the master prompt:

  1. Pre-migration assessment — probe an existing EJBCA / NDES SCEP
     server before switching to certctl to see what capabilities it
     advertises and what the CA cert looks like.
  2. Compliance posture audits — periodic ad-hoc probes against the
     operator's own SCEP servers to flag drift.

Capability-only — does NOT POST a CSR per the spec (would consume slot
allocations on the target server + create audit noise). Standalone CLI
binary explicitly out of scope (per the master prompt §11.5.6 and the
operator's confirmation): the probe code lands inside certctl; a
future thin Cobra wrapper is a separate decision.

Backend (six new + one extended file):

  * internal/domain/network_scan.go — new SCEPProbeResult struct with
    every probe field documented for the GUI's display layer.

  * migrations/000021_scep_probe_results.up.sql + .down.sql — new
    scep_probe_results table with TEXT id, target_url, all probe
    flags, CA cert metadata, probed_at, probe_duration_ms, error.
    Two indexes: idx_scep_probe_results_probed_at (DESC) for the
    'recent probes' GUI query, idx_scep_probe_results_target_url
    (target_url, probed_at DESC) for the future per-URL history view.

  * internal/repository/interfaces.go — new SCEPProbeResultRepository
    interface (Insert + ListRecent).

  * internal/repository/postgres/scep_probe_results.go — Postgres
    implementation. ListRecent clamps limit to [1, 200]; on read
    re-derives ca_cert_days_to_expiry against the query-time wall
    clock so 'X days remaining' stays fresh.

  * internal/service/scep_probe.go — ProbeSCEP(ctx, url) on
    NetworkScanService. Validation order:
      1. Up-front URL validation via validation.ValidateSafeURL
         (defaults to validation.ValidateSafeURL but injectable for
         tests via the new scepValidateURL field on the service).
      2. Dial-time SSRF re-check via SafeHTTPDialContext on the
         http.Transport (defends against DNS rebinding).
      3. GET ?operation=GetCACaps + GET ?operation=GetCACert.
         GetCACert handles three response shapes: PKCS#7 SignedData
         certs-only envelope (multi-cert), raw DER (single-cert),
         and PEM-wrapped DER (non-conforming servers).
    Times out at 30s; uses a 1MB body cap for DoS defense; wraps
    the result + persists via the repo (nil-safe) before returning.
    describeCertAlgorithm helper returns 'RSA-N' / 'ECDSA-curve' /
    'Ed25519' / 'DSA' for the GUI's algorithm column.

  * internal/service/network_scan.go — added scepProbeRepo +
    scepHTTPClient + scepValidateURL + scepIDFn + nowFn fields;
    SetSCEPProbeRepo wires the repo at startup.

  * internal/api/handler/network_scan.go — extended NetworkScanService
    interface with ProbeSCEP + ListRecentSCEPProbes; added two new
    HTTP handlers:
      POST /api/v1/network-scan/scep-probe   (body {url})
      GET  /api/v1/network-scan/scep-probes  (recent history)
    Synchronous probe; HTTP 200 with the result body for both success
    and reachable-but-failed cases (so the GUI can render the failure
    tone with the operator-actionable error message).

  * internal/api/router/router.go — registered the two routes inline
    after the existing network-scan target endpoints.

  * api/openapi.yaml — documented both endpoints (operationId
    probeSCEP + listSCEPProbes) with full schema + response codes.

  * cmd/server/main.go — wires the new SCEPProbeResultRepository
    onto the network scan service via SetSCEPProbeRepo right after
    the existing NewNetworkScanService construction.

Backend tests (6 new — exit-criteria-named per the master prompt):

  * TestProbeSCEP_AdvertisesAllCaps — happy path, full RFC 8894
    capability set, ECDSA P-256 CA cert, 365-day expiry.
  * TestProbeSCEP_MissingSCEPStandard — pre-RFC-8894 server (only
    POSTPKIOperation + SHA-1 + DES3); SupportsRFC8894 = false.
  * TestProbeSCEP_GetCACertExpired — CA cert NotAfter 30d in the
    past; CACertExpired = true.
  * TestProbeSCEP_Unreachable — connect to TCP port 1; probe
    returns Reachable=false + non-empty Error.
  * TestProbeSCEP_RejectsReservedIP — http://169.254.169.254/scep
    (EC2 metadata literal) rejected by the up-front
    validation.ValidateSafeURL gate; result captures the error
    without ever issuing the HTTP call.
  * TestProbeSCEP_PEMWrappedCert — server returns PEM instead of
    raw DER for GetCACert; the fallback parse path handles it.

Frontend (one extended file + types/client):

  * web/src/api/types.ts — SCEPProbeResult + SCEPProbesResponse.
  * web/src/api/client.ts — probeSCEPServer + listSCEPProbes
    helpers.
  * web/src/pages/NetworkScanPage.tsx — new SCEPProbeSection
    component + ProbeResultPanel (with capability badges + CA cert
    details panel + raw caps line) + SCEPProbeHistoryTable. Form
    rejects empty URL with inline error before calling the API.
    Reload mutation goes through useTrackedMutation with explicit
    invalidates: [['scep-probes']] (M-009 contract).

Frontend tests (5 new + 0 regressions):

  * Scep probe section header + form renders.
  * Empty URL is rejected with inline error and never calls the
    probe endpoint.
  * Successful probe renders capability badges + CA cert subject
    + days-remaining inline panel.
  * Probe-level errors are surfaced in the inline panel (no result
    panel rendered).
  * Recent-probes history table renders one row per probe.
  * (Existing 2 NetworkScanPage XSS-hardening tests stub the new
    listSCEPProbes endpoint to an empty list so they still pass.)

Verification:
  * gofmt clean on touched files
  * go vet ./... clean
  * staticcheck on service+handler+router+repository+cmd-server clean
  * go test -short across service+handler+router+repository+cmd-server
    + integration: all green (existing + 6 new probe tests pass)
  * Frontend tsc --noEmit clean
  * Vitest: 7/7 NetworkScanPage tests pass (2 existing XSS + 5 new
    probe section)
  * G-3 docs-drift CI guard reproduced locally clean (no new env vars)
  * M-009 hard-zero useMutation guard clean (probe mutation goes
    through useTrackedMutation)
  * openapi-parity guard satisfied (both new routes documented)
  * The mockNetworkScanService in handler + integration packages
    extended with stub Probe methods; targeted coverage stays in
    scep_probe_test.go.

Out of scope (per master prompt §11.5.6 + operator confirmation):
  * Standalone certctl-scan CLI binary — separate decision, ~1d of
    follow-up work when/if shipped.

Refs: cowork/scep-rfc8894-intune-master-prompt.md::Phase 11.5
      cowork/scep-rfc8894-intune/progress.md

internal/repository/postgres/scep_probe_results.go

@@ -0,0 +1,176 @@
+package postgres
+
+import (
+	"context"
+	"database/sql"
+	"fmt"
+	"time"
+
+	"github.com/lib/pq"
+	"github.com/shankar0123/certctl/internal/domain"
+	"github.com/shankar0123/certctl/internal/repository"
+)
+
+// SCEPProbeResultRepository is the PostgreSQL-backed implementation of
+// repository.SCEPProbeResultRepository.
+//
+// SCEP RFC 8894 + Intune master bundle Phase 11.5. Each row is one
+// completed probe run; the table accumulates history (no in-place
+// updates) so the GUI can show "recent probes" without losing the prior
+// snapshot's CA cert metadata.
+type SCEPProbeResultRepository struct {
+	db *sql.DB
+}
+
+// NewSCEPProbeResultRepository creates a new Postgres-backed repo.
+func NewSCEPProbeResultRepository(db *sql.DB) *SCEPProbeResultRepository {
+	return &SCEPProbeResultRepository{db: db}
+}
+
+// Insert persists a single probe result.
+func (r *SCEPProbeResultRepository) Insert(ctx context.Context, result *domain.SCEPProbeResult) error {
+	if result == nil {
+		return fmt.Errorf("scep probe result: nil")
+	}
+	_, err := r.db.ExecContext(ctx, `
+		INSERT INTO scep_probe_results (
+			id, target_url, reachable,
+			advertised_caps, supports_rfc8894, supports_aes,
+			supports_post_operation, supports_renewal,
+			supports_sha256, supports_sha512,
+			ca_cert_subject, ca_cert_issuer,
+			ca_cert_not_before, ca_cert_not_after, ca_cert_expired,
+			ca_cert_algorithm, ca_cert_chain_length,
+			probed_at, probe_duration_ms, error
+		) VALUES (
+			$1, $2, $3,
+			$4, $5, $6,
+			$7, $8,
+			$9, $10,
+			$11, $12,
+			$13, $14, $15,
+			$16, $17,
+			$18, $19, $20
+		)`,
+		result.ID, result.TargetURL, result.Reachable,
+		pq.Array(result.AdvertisedCaps), result.SupportsRFC8894, result.SupportsAES,
+		result.SupportsPOSTOperation, result.SupportsRenewal,
+		result.SupportsSHA256, result.SupportsSHA512,
+		nullString(result.CACertSubject), nullString(result.CACertIssuer),
+		nullTime(result.CACertNotBefore), nullTime(result.CACertNotAfter), result.CACertExpired,
+		nullString(result.CACertAlgorithm), result.CACertChainLength,
+		result.ProbedAt, result.ProbeDurationMs, nullString(result.Error),
+	)
+	if err != nil {
+		return fmt.Errorf("insert scep probe result: %w", err)
+	}
+	return nil
+}
+
+// ListRecent returns the most recent N probe results across any URL,
+// ordered by probed_at descending. limit is clamped to [1, 200] to bound
+// the response size — the GUI defaults to 50.
+func (r *SCEPProbeResultRepository) ListRecent(ctx context.Context, limit int) ([]*domain.SCEPProbeResult, error) {
+	if limit <= 0 {
+		limit = 50
+	}
+	if limit > 200 {
+		limit = 200
+	}
+	rows, err := r.db.QueryContext(ctx, `
+		SELECT id, target_url, reachable,
+		       advertised_caps, supports_rfc8894, supports_aes,
+		       supports_post_operation, supports_renewal,
+		       supports_sha256, supports_sha512,
+		       ca_cert_subject, ca_cert_issuer,
+		       ca_cert_not_before, ca_cert_not_after, ca_cert_expired,
+		       ca_cert_algorithm, ca_cert_chain_length,
+		       probed_at, probe_duration_ms, error,
+		       created_at
+		FROM scep_probe_results
+		ORDER BY probed_at DESC
+		LIMIT $1`,
+		limit,
+	)
+	if err != nil {
+		return nil, fmt.Errorf("list recent scep probe results: %w", err)
+	}
+	defer rows.Close()
+
+	var out []*domain.SCEPProbeResult
+	for rows.Next() {
+		var (
+			row       domain.SCEPProbeResult
+			subject   sql.NullString
+			issuer    sql.NullString
+			notBefore sql.NullTime
+			notAfter  sql.NullTime
+			algorithm sql.NullString
+			errString sql.NullString
+		)
+		err := rows.Scan(
+			&row.ID, &row.TargetURL, &row.Reachable,
+			pq.Array(&row.AdvertisedCaps), &row.SupportsRFC8894, &row.SupportsAES,
+			&row.SupportsPOSTOperation, &row.SupportsRenewal,
+			&row.SupportsSHA256, &row.SupportsSHA512,
+			&subject, &issuer,
+			&notBefore, &notAfter, &row.CACertExpired,
+			&algorithm, &row.CACertChainLength,
+			&row.ProbedAt, &row.ProbeDurationMs, &errString,
+			&row.CreatedAt,
+		)
+		if err != nil {
+			return nil, fmt.Errorf("scan scep probe result row: %w", err)
+		}
+		if subject.Valid {
+			row.CACertSubject = subject.String
+		}
+		if issuer.Valid {
+			row.CACertIssuer = issuer.String
+		}
+		if notBefore.Valid {
+			row.CACertNotBefore = notBefore.Time
+		}
+		if notAfter.Valid {
+			row.CACertNotAfter = notAfter.Time
+			if !row.CACertExpired {
+				// Re-derive days_to_expiry on read so it reflects the
+				// query-time wall clock rather than the persisted
+				// snapshot's wall clock — operators care about how
+				// fresh "30d remaining" is.
+				hours := time.Until(notAfter.Time).Hours()
+				row.CACertDaysToExpiry = int(hours / 24)
+			}
+		}
+		if algorithm.Valid {
+			row.CACertAlgorithm = algorithm.String
+		}
+		if errString.Valid {
+			row.Error = errString.String
+		}
+		out = append(out, &row)
+	}
+	if err := rows.Err(); err != nil {
+		return nil, fmt.Errorf("iterate scep probe results: %w", err)
+	}
+	return out, nil
+}
+
+// nullString returns sql.NullString — empty becomes NULL.
+func nullString(s string) sql.NullString {
+	if s == "" {
+		return sql.NullString{}
+	}
+	return sql.NullString{String: s, Valid: true}
+}
+
+// nullTime returns sql.NullTime — zero time becomes NULL.
+func nullTime(t time.Time) sql.NullTime {
+	if t.IsZero() {
+		return sql.NullTime{}
+	}
+	return sql.NullTime{Time: t, Valid: true}
+}
+
+// Compile-time interface check.
+var _ repository.SCEPProbeResultRepository = (*SCEPProbeResultRepository)(nil)