auth-bundle-1 Phase 6-7-8: bootstrap path + scope-down CLI + auditor-role split

# Phase 6 — day-0 admin bootstrap

* internal/auth/bootstrap/ (new package): Strategy interface +
  EnvTokenStrategy with constant-time compare, one-shot consumption
  via sync.Mutex, optional admin-existence probe. Bundle 2's OIDC-
  first-admin will plug in alongside as an alternate Strategy.
* BootstrapService.ValidateAndMint: validates the operator's
  CERTCTL_BOOTSTRAP_TOKEN, mints a 32-byte (64-hex-char) random API
  key value, persists the SHA-256 hash to api_keys, grants r-admin
  via actor_roles, AddHashed's the runtime keystore so the just-
  minted key authenticates the next request without restart, and
  records bootstrap.consume to the audit trail with category=auth.
* internal/auth/keystore.go (new): KeyStore interface +
  StaticKeyStore (immutable env-var-only path) + MutableKeyStore
  (env-var keys + DB-loaded api_keys + runtime AddHashed). The auth
  middleware now consumes a KeyStore so the bootstrap path can
  extend the lookup table at runtime.
* migrations/000031_api_keys.up/down.sql: api_keys table with
  (id, name UNIQUE, key_hash UNIQUE, tenant_id, admin, created_by,
  created_at, expires_at, last_used_at). Idempotent.
* /v1/auth/bootstrap GET (probe) + POST (mint) — auth-exempt. Both
  routes documented in api/openapi.yaml + AuthExemptRouterRoutes
  allowlist updated. The token never leaves internal/auth/bootstrap;
  the minted plaintext key flows only into the HTTP response body.
* Startup warning emitted when CERTCTL_BOOTSTRAP_TOKEN is set AND
  admin actors already exist (config drift signal).
* Tests: 4 strategy invariants (empty token born disabled, wrong
  token=ErrInvalidToken without consumption, one-shot consumption,
  admin-exists closes path), 5 service tests (happy path + actor-
  name validation + propagation of strategy errors + nil-deps
  guard + 32-byte entropy budget), 8 HTTP-handler tests (status
  201/410/401/400 mapping + token-leak hygiene scan of slog +
  audit details + Location header). Token-leak test redirects
  slog.Default to a buffer for the test scope.

# Phase 7 — API-key migration + scope-down CLI

* GET /v1/auth/keys handler + service method ListKeys backed by
  ActorRoleRepository.ListDistinctActors. Returns one row per
  (actor_id, actor_type) pair with the slice of role IDs they hold.
  Permission: auth.role.list.
* internal/cli/auth_scope_down.go: AuthListKeys, AuthScopeDown
  (interactive), AuthScopeDownNonInteractive (JSON config),
  AuthScopeDownSuggest (--suggest with optional --apply). The
  synthetic actor-demo-anon is filtered out of every interactive /
  bulk path; non-interactive flow logs and skips it explicitly.
* SuggestRoleFromAuditEvents (pure function): walks 30 days of
  audit events per actor and returns the narrowest matching role
  (admin / mcp / viewer / agent / operator) plus a one-line reason.
  Classification: any admin-shaped action wins; otherwise all-MCP
  → mcp; all-read-only → viewer; all-agent-shaped → agent;
  otherwise operator. Test table pins all six classifications.
* CLI subcommand tree extended: 'auth keys list' + 'auth keys
  scope-down [--non-interactive <cfg>] [--suggest [--apply]]'.
* CHANGELOG.md leads v2.1.0 with the SECURITY: AUDIT YOUR API KEYS
  call-out + four flow examples.

# Phase 8 — auditor role + event_category column

* migrations/000032_audit_category.up/down.sql: ALTER TABLE
  audit_events ADD COLUMN event_category TEXT NOT NULL DEFAULT
  'cert_lifecycle' + CHECK constraint (cert_lifecycle/auth/config)
  + (event_category) and (event_category, timestamp DESC) indexes
  for the auditor-filter query path. WORM trigger from migration
  000018 continues to enforce append-only at the DB layer (DDL is
  not blocked).
* domain.AuditEvent gains EventCategory string (omitempty);
  domain.EventCategoryCertLifecycle / Auth / Config constants.
* AuditService.RecordEventWithCategory sibling of RecordEvent;
  legacy callers stay on RecordEvent (defaults to cert_lifecycle).
  Auth callers (RoleService, ActorRoleService, BootstrapService)
  switched to RecordEventWithCategory(..., 'auth', ...).
* GET /v1/audit?category=<cat>: handler accepts the optional query
  param, validates against the enum (400 on invalid value),
  dispatches through ListAuditEventsByCategory. OpenAPI updated
  with the new query param + AuditEvent.event_category schema.
* Postgres AuditRepository.Create now writes event_category;
  AuditRepository.List filters on it; AuditFilter.EventCategory
  gates the WHERE clause.
* Tests: 5 audit-category-filter HTTP tests (dispatch routing,
  back-compat fallback, 400 for invalid values, all 3 enum values
  accepted, page+category combine, JSON output surfaces the
  field). 3 auditor-role invariants (auditor holds exactly
  audit.read+audit.export, no mutating perms, disjoint from
  viewer except audit.read).

# Cross-phase wiring

* HandlerRegistry.Bootstrap field added; cmd/server/main.go wires
  the bootstrap service ahead of RegisterHandlers (extracted
  assembleNamedAPIKeys helper into auth_backfill.go, moved the
  keystore + bootstrap construction up alongside the auth repos).
* AuthCheckResolver / AuthActorRoleService extended with ListKeys
  to satisfy the Phase 7 surface; existing fakes updated.
* fakeAudit + mockAuditService stubs in tests gain
  RecordEventWithCategory + ListAuditEventsByCategory; existing
  tests untouched.

# Verifications

* gofmt -l: clean across every modified file.
* go vet ./...: clean.
* staticcheck across internal/auth + handler + router + cli +
  service + repository + cmd + domain: clean.
* go test -short -count=1: green across every Bundle-1-touched
  package — internal/auth (incl. bootstrap), internal/api/handler,
  internal/api/router, internal/cli, internal/service/auth,
  internal/service, internal/domain/auth, internal/repository/postgres,
  cmd/server, cmd/cli, plus internal/scheduler, internal/api/middleware,
  cmd/agent, internal/mcp.

internal/repository/auth.go

@@ -101,6 +101,40 @@ type ActorRoleRepository interface {
 	// gated request; implementations should cache or use SQL JOINs
 	// for performance.
 	EffectivePermissions(ctx context.Context, actorID string, actorType authdomain.ActorTypeValue, tenantID string) ([]EffectivePermission, error)
+
+	// AdminExists reports whether ANY actor in the tenant currently
+	// holds the r-admin role. Bundle 1 Phase 6's bootstrap probe
+	// uses this to gate the day-0 endpoint: once the answer flips
+	// from false to true the bootstrap path stays closed forever
+	// (the seeded actor-demo-anon admin only exists in demo mode;
+	// in api-key mode the operator either uses bootstrap or
+	// CERTCTL_API_KEYS_NAMED to mint the first admin). The query
+	// excludes the synthetic actor-demo-anon so demo-mode deploys
+	// can still bootstrap a real admin if/when the operator
+	// switches to api-key mode without re-migrating.
+	AdminExists(ctx context.Context, tenantID string) (bool, error)
+
+	// ListDistinctActors returns one row per (actor_id, actor_type)
+	// pair with at least one actor_roles grant in the tenant.
+	// Bundle 1 Phase 7's `auth keys list` + scope-down helper use
+	// this to enumerate the actor population without joining
+	// against the env-var-loaded namedKeys (whose canonical record
+	// is the actor_roles backfill from Phase 1 / C2). The synthetic
+	// actor-demo-anon is included so the GUI can render it as
+	// "system-managed, scope-down hidden"; Phase 7's interactive
+	// flow filters it out of the prompt loop.
+	ListDistinctActors(ctx context.Context, tenantID string) ([]ActorWithRoles, error)
+}
+
+// ActorWithRoles is the (actor, roles) projection returned by
+// ActorRoleRepository.ListDistinctActors. Roles is the slice of role
+// IDs the actor holds; the caller can resolve role names via the
+// RoleRepository or the CLI's already-cached role list.
+type ActorWithRoles struct {
+	ActorID   string
+	ActorType authdomain.ActorTypeValue
+	TenantID  string
+	RoleIDs   []string
 }
 
 // EffectivePermission is the (permission, scope) pair returned by
@@ -112,3 +146,25 @@ type EffectivePermission struct {
 	ScopeType      authdomain.ScopeType
 	ScopeID        *string // NULL = global
 }
+
+// APIKeyRepository wraps the api_keys table. Bundle 1 Phase 6 ships
+// this so the bootstrap endpoint (POST /v1/auth/bootstrap) can mint
+// the first admin API key without needing the operator to roundtrip
+// through CERTCTL_API_KEYS_NAMED. Operator-tier keys live here;
+// agent-tier keys remain on the agents table (`api_key_hash` column).
+type APIKeyRepository interface {
+	// Create stores a new key row. ID + CreatedAt default if zero.
+	// The plaintext key is NOT stored — callers pass only the
+	// SHA-256 hex hash. Returns ErrAuthDuplicateName when the
+	// (name) UNIQUE constraint fires.
+	Create(ctx context.Context, key *authdomain.APIKey) error
+	// GetByName returns a single row by operator-visible name.
+	// Returns ErrAuthNotFound when no row matches.
+	GetByName(ctx context.Context, name string) (*authdomain.APIKey, error)
+	// List returns every key row across the tenant. Bundle 1 ships
+	// single-tenant so tenantID is typically t-default.
+	List(ctx context.Context, tenantID string) ([]*authdomain.APIKey, error)
+	// Delete removes a key row by name. Used by the RBAC API's key
+	// rotation/revocation paths.
+	Delete(ctx context.Context, name string) error
+}