fix(auth/rbac): scope-aware ActorRole revoke (A-4)

HIGH-10's UNIQUE (actor, role, scope_type, scope_id, tenant) uniqueness
extension lets an operator grant the same role to the same actor at
multiple scopes (e.g. r-operator on profile=p-acme AND profile=p-globex).
But ActorRoleRepository.Revoke's WHERE clause omitted (scope_type,
scope_id) — a single call deleted every variant. Selective revoke was
unrepresentable; operators had to drop all and re-grant N-1, opening
a race window where the actor's access was briefly different.

Closure across all layers (handler → service → repo → MCP → GUI client),
preserving the legacy "revoke all variants" contract for unmodified
callers:

  internal/repository/auth.go
    - New ActorRoleRevokeOptions struct. Zero value = legacy semantic;
      non-empty ScopeType narrows to one variant.
    - New ErrActorRoleNotFound sentinel for scoped no-match (HTTP 404).

  internal/repository/postgres/auth.go
    - Revoke signature extended with opts. Empty opts.ScopeType uses
      the legacy SQL (no scope WHERE), zero-row delete = no error.
    - Non-empty narrows with `scope_type = $5 AND scope_id IS NOT
      DISTINCT FROM $6` — the IS-NOT-DISTINCT-FROM is load-bearing,
      vanilla `=` would silently miss the (global, NULL) case because
      NULL ≠ NULL in standard SQL.
    - Selective revoke with zero matching rows returns
      ErrActorRoleNotFound; operators get feedback on typos.

  internal/service/auth/actor_role_service.go
    - Revoke takes opts. Audit row's details map records the scope so
      SIEMs can distinguish wide-vs-selective revokes:
      `scope: "all_variants"` for the legacy path, or
      `scope_type` + `scope_id` for selective. Privilege check
      (auth.role.assign) and reserved-actor guard unchanged.

  internal/api/handler/auth.go
    - RevokeRoleFromKey parses optional `?scope_type=` / `?scope_id=`
      query params via new parseRevokeScope helper.
    - Validation mirrors AssignRoleToKey: scope_id forbidden with
      scope_type=global, required with profile/issuer, invalid
      scope_type → 400. scope_id without scope_type also → 400.
    - writeAuthError maps ErrActorRoleNotFound to 404.

  internal/mcp/tools_auth.go + types.go
    - AuthRevokeKeyRoleInput gains optional ScopeType + ScopeID with
      jsonschema descriptions explaining the dual-mode contract.
    - Tool call site appends URL-encoded query params when ScopeType
      is set; legacy callers (no scope_type) emit the bare DELETE
      path unchanged.

  web/src/api/client.ts
    - authRevokeKeyRole signature: optional 3rd argument
      `{ scope_type?, scope_id? }`. Pre-A-4 call sites (no opts arg)
      keep firing the bare DELETE — fully backward compatible. The
      GUI KeysPage's per-row revoke button (still one row per role,
      pre-Fix-12) continues to use the legacy shape; future GUI work
      can pass scope params for per-variant rows.

  docs/operator/rbac.md
    - New "Revoke: legacy 'all variants' vs scope-selective" subsection
      under "From the HTTP API" with curl examples for both modes plus
      the audit-row payload shape that lets SOC/SIEM tell them apart.

Regression coverage:

  Repository (testcontainers, skipped under -short — 6 tests in
  internal/repository/postgres/auth_revoke_scope_test.go):
    TestRevokeActorRole_NoOpts_RemovesAllVariants
    TestRevokeActorRole_WithScope_RemovesOnlyMatching
    TestRevokeActorRole_WithGlobalScope_RemovesOnlyGlobal — pins the
      IS-NOT-DISTINCT-FROM branch (global, NULL)
    TestRevokeActorRole_NoMatch_ReturnsNotFound — pins the new sentinel
    TestRevokeActorRole_NoOpts_NoMatch_IsNoOp — pins the legacy
      idempotence contract
    TestRevokeActorRole_IssuerScope_RemovesOnlyMatching — pin the
      issuer-scope half (profile + issuer are symmetric scope types)

  Handler (7 new tests in auth_test.go):
    TestAuthHandler_RevokeRoleFromKey — extended to assert no scope
      filter is forwarded when query string is empty (legacy behaviour)
    TestAuthHandler_RevokeRoleFromKey_A4_ScopedProfile
    TestAuthHandler_RevokeRoleFromKey_A4_ScopedGlobal
    TestAuthHandler_RevokeRoleFromKey_A4_RejectsScopeIDWithGlobal
    TestAuthHandler_RevokeRoleFromKey_A4_RejectsMissingScopeID
    TestAuthHandler_RevokeRoleFromKey_A4_RejectsScopeIDWithoutScopeType
    TestAuthHandler_RevokeRoleFromKey_A4_RejectsInvalidScopeType
    TestAuthHandler_RevokeRoleFromKey_A4_ScopedNotFoundReturns404

  MCP (2 new table rows in tools_per_tool_test.go):
    Scoped revoke with scope_type=profile + scope_id=p-acme →
      `?scope_type=profile&scope_id=p-acme`
    Scoped revoke with scope_type=global (no scope_id) →
      `?scope_type=global`

Service-layer test plumbing (service_test.go) updated for new opts
arg: 4 existing call sites pass repository.ActorRoleRevokeOptions{}
to keep their pre-A-4 semantics; the fakeActorRoleRepo.Revoke
implementation now mirrors the postgres scope-aware behaviour
(legacy zero-value vs scoped narrowing + ErrActorRoleNotFound on
no-match).

Verify gate green: gofmt clean, go vet clean, go test -short across
repository/postgres, service/auth, api/handler, and mcp. The
pre-existing KeysPage.test.tsx failure observed on the baseline
commit (reproduced via `git stash` earlier in Fix 03) is unrelated;
my client.ts change adds an optional third argument and is fully
backward-compatible.

Spec at cowork/auth-bundles-fixes-2026-05-11/04-high-actor-role-revoke-scope.md.
Audit doc updated: new row A-4 (2026-05-11) CLOSED appended to the
status table at the bottom of cowork/auth-bundles-audit-2026-05-10.md.
Operator-visible advisory in CHANGELOG.md v2.1.0 release notes under
Security (non-BREAKING — legacy callers are unchanged).

Depends on Fix 01 (the scope-aware EffectivePermissions read path on
branch fix/audit-2026-05-11/crit-actor-role-scope-reads). This fix
makes the inverse op selectively reversible; without Fix 01 the read
side would mis-evaluate scoped grants anyway, making selective revoke
moot at runtime.

internal/repository/auth.go

@@ -32,8 +32,46 @@ var (
 	// references a permission name not in the canonical catalog.
 	// Maps to HTTP 400.
 	ErrAuthUnknownPermission = errors.New("auth: permission not in canonical catalog")
+
+	// ErrActorRoleNotFound is returned by ActorRoleRepository.Revoke
+	// when the caller passes a non-empty `RevokeOptions.ScopeType` that
+	// doesn't match any persisted (actor, role, scope_type, scope_id)
+	// tuple. The legacy no-opts "revoke all variants" call never
+	// returns this — pre-A-4 callers cannot start seeing the error.
+	// Maps to HTTP 404. Audit 2026-05-11 A-4.
+	ErrActorRoleNotFound = errors.New("auth: no actor_role row matches the requested scope")
 )
 
+// ActorRoleRevokeOptions narrows ActorRoleRepository.Revoke to a
+// specific (scope_type, scope_id) variant when set. Audit 2026-05-11
+// A-4 — HIGH-10's UNIQUE (actor, role, scope_type, scope_id, tenant)
+// uniqueness extension allows multiple scoped grants of the same role
+// to the same actor; without scope plumbing on Revoke an operator who
+// granted Alice `r-operator` against both `profile=p-acme` and
+// `profile=p-globex` cannot selectively revoke one.
+//
+// Semantics:
+//
+//   - Zero value (ScopeType="") preserves the legacy "revoke all
+//     variants" behaviour. Every actor_roles row matching
+//     (actor_id, actor_type, role_id, tenant_id) is deleted regardless
+//     of scope. Pre-A-4 callers that don't pass options stay correct.
+//
+//   - Non-empty ScopeType filters to that one variant. `global`
+//     requires ScopeID==nil; `profile` / `issuer` require
+//     ScopeID!=nil. The SQL uses `scope_type = $5 AND scope_id IS NOT
+//     DISTINCT FROM $6` so the NULL case matches cleanly.
+//
+//   - If the filter doesn't match any row, the repository returns
+//     ErrActorRoleNotFound — the caller (service / handler) maps it
+//     to HTTP 404. The legacy "revoke all" semantic stays best-effort
+//     (deleting zero rows is not an error) because the GUI used to
+//     fire it as a clean-up and operators rely on the idempotence.
+type ActorRoleRevokeOptions struct {
+	ScopeType authdomain.ScopeType
+	ScopeID   *string
+}
+
 // TenantRepository wraps the tenants table. Bundle 1 ships single-tenant
 // (one seeded `t-default`); the future managed-service offering activates
 // multi-tenant by inserting additional tenants.
@@ -89,10 +127,15 @@ type ActorRoleRepository interface {
 	// only if the operator explicitly wires that, which the API
 	// layer rejects.
 	Grant(ctx context.Context, ar *authdomain.ActorRole) error
-	// Revoke deletes an actor_roles row by (actor_id, actor_type,
-	// role_id, tenant_id). The API layer must reject revocations
-	// targeting `actor-demo-anon` to preserve the demo path.
-	Revoke(ctx context.Context, actorID string, actorType authdomain.ActorTypeValue, roleID, tenantID string) error
+	// Revoke deletes actor_roles row(s). Without opts (the legacy
+	// no-options call shape) every variant matching
+	// (actor_id, actor_type, role_id, tenant_id) is deleted regardless
+	// of (scope_type, scope_id). With opts.ScopeType set, only the
+	// matching variant is deleted; no-match returns
+	// ErrActorRoleNotFound. The API layer must reject revocations
+	// targeting `actor-demo-anon` to preserve the demo path. Audit
+	// 2026-05-11 A-4 — see ActorRoleRevokeOptions for semantics.
+	Revoke(ctx context.Context, actorID string, actorType authdomain.ActorTypeValue, roleID, tenantID string, opts ActorRoleRevokeOptions) error
 
 	// EffectivePermissions returns the deduplicated set of
 	// (permission_name, scope_type, scope_id) triples granted to the