acme-server: orders + authorizations + finalize + cert download (Phase 2/7)

Closes the issuance loop in trust_authenticated mode (commits ec88a61
+ 44a85d6 wired the foundation + JWS-verified account resource).
After this commit, an ACME client running against a profile with
acme_auth_mode='trust_authenticated' end-to-end-issues a real cert:

  POST /acme/profile/<id>/new-order      → 201 + order URL (status=ready)
  POST /acme/profile/<id>/order/<oid>    → POST-as-GET fetch
  POST /acme/profile/<id>/order/<oid>/finalize  → 200 + status=valid + cert URL
  POST /acme/profile/<id>/cert/<cid>     → 200 + PEM chain

Profiles with acme_auth_mode='challenge' get the same code path with
authz/challenge rows in `pending` state until Phase 3's validators
wire up. The mode is read from the bound profile's column at request
time, NOT cached at server start — operators flipping the column via
SQL take effect on the next order without restart.

Architecture (the load-bearing part):
  - Finalize routes through service.CertificateService.Create — the
    canonical certctl issuance entry point that wraps the
    managed_certificates row insert + audit row in s.tx.WithinTx.
    RenewalPolicy / CertificateProfile / per-issuer-type Prometheus
    metrics / audit rows all apply uniformly to ACME-issued certs via
    the same code path that already serves EST/SCEP/agent/REST issuance.
  - Identifier validation runs BEFORE order creation. Rejected
    identifiers return RFC 7807 with per-identifier subproblems and
    create no order row.
  - Source stamp on managed_certificates: domain.CertificateSourceACME.
    Operators bulk-revoke ACME-issued certs by filtering on Source=ACME.
  - 3-step atomicity boundary documented in code + this commit msg:
    (A) WithinTx-A marks order processing + audit row.
    (B) IssuerConnector.IssueCertificate + CertificateService.Create
        (each in its own WithinTx — Create wraps cert row + audit
        atomically).
    (C) WithinTx-C creates certificate_versions row + transitions order
        to valid + sets certificate_id + audit row.
    The brief window between B and C can leave a managed_certificates
    row whose order is still in `processing`. Phase 5's GC scheduler
    reconciles. Documented inline.

What ships:
  - internal/api/acme/order.go: OrderResponseJSON + AuthorizationResponseJSON
    + ChallengeResponseJSON + NewOrderRequest + FinalizeRequest wire
    shapes; ValidateIdentifiers (Phase 2 syntactic checks, dns-only);
    CSRMatchesIdentifiers (RFC 8555 §7.4 strict equality, case-folded).
  - internal/domain/acme.go: ACMEOrder + ACMEAuthorization + ACMEChallenge
    + ACMEIdentifier + ACMEProblem domain types + closed status enums
    for each (order: pending|ready|processing|valid|invalid; authz:
    pending|valid|invalid|deactivated|expired|revoked; challenge:
    pending|processing|valid|invalid; challenge type: http-01|dns-01|
    tls-alpn-01).
  - internal/domain/profile.go: new ACMEAuthMode field reading from
    certificate_profiles.acme_auth_mode (added in migration 25).
  - internal/domain/certificate.go: new CertificateSourceACME enum value.
  - internal/repository/postgres/profile.go: extended SELECT/scanProfile
    to read the per-profile acme_auth_mode column with a COALESCE
    default of trust_authenticated.
  - internal/repository/postgres/acme.go: full order/authz/challenge
    CRUD (CreateOrderWithTx + GetOrderByID + UpdateOrderWithTx +
    CreateAuthzWithTx + GetAuthzByID + ListAuthzsByOrder +
    ListChallengesByAuthz + CreateChallengeWithTx) with proper
    sql.NullTime + JSONB handling. scanACMEOrder /
    scanACMEAuthz / scanACMEChallenge helpers.
  - internal/service/acme.go: extended ACMERepo interface; new
    SetIssuancePipeline wires certificateService + certificateRepo +
    issuerRegistry. CreateOrder (auth-mode-dispatched: trust_authenticated
    auto-marks order ready + authz valid + 1 placeholder http-01
    challenge valid; challenge mode keeps everything pending). LookupOrder
    (with account-ownership assertion). LookupAuthz. ListAuthzsByOrder.
    FinalizeOrder (3-step atomicity boundary as above; CSR-vs-order
    SAN strict-equality check before issuance; persists FinalizeOrderResult
    {Order, CertID}). LookupCertificate. randIDSuffix + base32encode
    helpers for the human-readable acme-ord-* / acme-authz-* /
    acme-chall-* prefixes (CLAUDE.md "TEXT primary keys with human-
    readable prefixes" architecture decision). 8 new per-op metrics.
  - internal/service/acme_test.go: extended fakeACMERepo with Phase 2
    interface stubs; new orderTrackingRepo for observable persistence;
    2 new tests asserting trust_authenticated → auto-ready/valid and
    challenge → stays-pending.
  - internal/api/handler/acme.go: NewOrder + Order + OrderFinalize +
    Authz + Cert handler methods. orderURL / authzURL / certURL /
    challengeURLBuilder helpers; marshalOrderForResponse fetches
    per-order authzs to populate the URL list. parseOptionalTime for
    notBefore / notAfter.
  - internal/api/handler/acme_handler_test.go: extended mockACMEService
    with Phase 2 method stubs; 4 new handler tests (NewOrder happy +
    rejected-identifier + OrderFinalize bad-CSR + Cert happy).
  - internal/api/router/router.go: 10 new Register calls (5 per-profile
    + 5 shorthand) for new-order, order/{ord_id}, order/{ord_id}/finalize,
    authz/{authz_id}, cert/{cert_id}.
  - internal/api/router/openapi_parity_test.go + api/openapi-handler-exceptions.yaml:
    10 new exception entries.
  - cmd/server/main.go: SetIssuancePipeline at startup, threading
    certificateService + certificateRepo + issuerRegistry into ACMEService.
  - docs/acme-server.md: phase status updated; endpoints table grows
    5 rows for new-order/order/finalize/authz/cert (per-profile +
    shorthand variants); new section "Finalize routing through
    CertificateService.Create" documenting the 3-step atomicity
    boundary + the actor-string convention `acme:<account-id>`.

Tests: ACME package + service + handler + router + config + domain
all green under -short. New cases:
  - TestCreateOrder_TrustAuthenticated_AutoReady (asserts auto-ready
    transition + valid-status authz/challenge + audit row + metric bump).
  - TestCreateOrder_ChallengeMode_StaysPending (asserts pending-status
    cascading authz/challenge for challenge mode).
  - TestACMEHandler_NewOrder_HappyPath (asserts 201 + Location +
    finalize URL shape).
  - TestACMEHandler_NewOrder_RejectedIdentifier (asserts 400 + RFC 7807
    rejectedIdentifier + per-identifier subproblems for type=ip).
  - TestACMEHandler_OrderFinalize_BadCSR (asserts 400 + badCSR for
    non-base64 CSR field).
  - TestACMEHandler_Cert_HappyPath (asserts 200 + PEM content-type +
    PEM chain in body).

Engineering history: cowork/WORKSPACE-CHANGELOG.md "ACME-Server-2".

api/openapi-handler-exceptions.yaml

@@ -54,3 +54,25 @@ documented_exceptions:
     why: "ACME server default-profile shorthand for new-account."
   - route: "POST /acme/account/{acc_id}"
     why: "ACME server default-profile shorthand for account update + deactivation."
+
+  # Phase 2 — orders + finalize + authz + cert.
+  - route: "POST /acme/profile/{id}/new-order"
+    why: "ACME server RFC 8555 §7.4 new-order; documented in docs/acme-server.md."
+  - route: "POST /acme/profile/{id}/order/{ord_id}"
+    why: "ACME server RFC 8555 §7.4 order POST-as-GET; documented in docs/acme-server.md."
+  - route: "POST /acme/profile/{id}/order/{ord_id}/finalize"
+    why: "ACME server RFC 8555 §7.4 finalize; documented in docs/acme-server.md."
+  - route: "POST /acme/profile/{id}/authz/{authz_id}"
+    why: "ACME server RFC 8555 §7.5 authz POST-as-GET; documented in docs/acme-server.md."
+  - route: "POST /acme/profile/{id}/cert/{cert_id}"
+    why: "ACME server RFC 8555 §7.4.2 cert download; documented in docs/acme-server.md."
+  - route: "POST /acme/new-order"
+    why: "Phase 2 default-profile shorthand for new-order."
+  - route: "POST /acme/order/{ord_id}"
+    why: "Phase 2 default-profile shorthand for order POST-as-GET."
+  - route: "POST /acme/order/{ord_id}/finalize"
+    why: "Phase 2 default-profile shorthand for finalize."
+  - route: "POST /acme/authz/{authz_id}"
+    why: "Phase 2 default-profile shorthand for authz POST-as-GET."
+  - route: "POST /acme/cert/{cert_id}"
+    why: "Phase 2 default-profile shorthand for cert download."