feat(gui+auth): break-glass admin GUI surface (CRIT-4 closure)

Closes CRIT-4 of the 2026-05-10 audit. Bundle 2 Phase 7.5 shipped the
break-glass backend (Argon2id + lockout + 4 endpoints) but no GUI
surface. Operators recovering during an SSO outage had to hand-craft
curl commands — operationally hostile and the opposite of what
docs/operator/security.md advertised. This commit closes the gap.

Three GUI surfaces:

1. LoginPage.tsx — inline "Use break-glass account (SSO outage
   recovery)" toggle below the API-key form. Clicking reveals an
   amber-bordered inline form (actor-id + password, autocomplete=off).
   Calls breakglassLogin(actor_id, password); on success navigates
   to "/" where AuthProvider re-validates via the session-cookie path.
   Intentionally low-visibility (text-amber-600 small text) — this is
   the deliberate-bypass path, not the everyday-login path.

2. web/src/pages/auth/BreakglassPage.tsx — admin page at /auth/breakglass
   (permission-gated by auth.breakglass.admin). Three sections:
     - Sticky security banner ("every action audited; use only during
       incidents").
     - Set/rotate-password form (≥12-char + confirm-match).
     - Credentialed-actor table with rotate / unlock (disabled when
       not locked) / remove per row. Remove requires type-the-actor-id
       confirmation.

3. Layout.tsx nav — "Break-glass" entry under the auth section. Visible
   to all callers; the page itself permission-gates (server-side 403 is
   the load-bearing defense). Cosmetic hide-when-no-perm is deferred
   to fix 14's LOW bundle.

Backend support (new endpoint required to enumerate credentialed actors):

- internal/repository/breakglass.go — BreakglassCredentialRepository
  gains List(ctx, tenantID) method.
- internal/repository/postgres/breakglass.go — postgres impl; reuses
  the existing breakglassColumns / scanBreakglass helpers.
- internal/auth/breakglass/service.go — Service.List(ctx) method;
  returns ErrDisabled when CERTCTL_BREAKGLASS_ENABLED=false (handler
  maps to 404 for surface invisibility).
- internal/api/handler/auth_breakglass.go — ListCredentials handler;
  password_hash field NEVER serialized to the wire (response shape
  is intentionally limited to actor_id + timestamps + failure_count +
  locked_until).
- internal/api/router/router.go — registers GET
  /api/v1/auth/breakglass/credentials gated by auth.breakglass.admin.
- internal/api/router/openapi_parity_test.go — SpecParityExceptions
  entry for the new endpoint (full OpenAPI row rides along with the
  next OpenAPI sweep).

GUI api/client.ts gains breakglassListCredentials() + the
BreakglassCredentialRow type matching the wire shape.

Six Vitest cases in BreakglassPage.test.tsx pin the contract:
permission gate (forbidden state when caller lacks the perm; admin
surface when they have it), set-password mismatch rejection, set-
password below-threshold-length rejection, unlock-disabled-when-not-
locked, remove-modal type-confirm.

Verification gate green:
- gofmt -l clean on all touched files
- go vet clean
- go test -short -count=1 on internal/api/router (TestRouter_OpenAPIParity
  + TestRouterRBACGateCoverage + TestRouter_AuthExemptAllowlist),
  internal/api/handler (all BCL tests + ListCredentials),
  internal/auth/breakglass (Service.List + stubRepo.List),
  internal/repository/postgres, internal/domain/auth (auditor pin)
  — all pass.

CRIT-1 + CRIT-2 + CRIT-3 from the same audit are already closed on
this branch (commits 68ca42f, ca1e135, 00eace8). CRIT-5 (AllowedEmail-
Domains lying field) remains the last Critical blocker for v2.1.0.
Spec: cowork/auth-bundles-fixes-2026-05-10/04-crit-4-breakglass-gui.md.

Refs: cowork/auth-bundles-audit-2026-05-10.md CRIT-4

web/src/components/Layout.tsx

@@ -33,6 +33,8 @@ const nav = [
   { to: '/auth/roles',    label: 'Roles',         icon: 'M16 7a4 4 0 11-8 0 4 4 0 018 0zM12 14a7 7 0 00-7 7h14a7 7 0 00-7-7z' },
   { to: '/auth/keys',      label: 'API Keys',      icon: 'M15 7a2 2 0 012 2m4 0a6 6 0 01-7.743 5.743L11 17H9v2H7v2H4a1 1 0 01-1-1v-2.586a1 1 0 01.293-.707l5.964-5.964A6 6 0 1121 9z' },
   { to: '/auth/approvals', label: 'Approvals',     icon: 'M9 12l2 2 4-4m6 2a9 9 0 11-18 0 9 9 0 0118 0z' },
+  // Audit 2026-05-10 CRIT-4 closure — break-glass admin surface.
+  { to: '/auth/breakglass', label: 'Break-glass',  icon: 'M12 9v2m0 4h.01m-6.938 4h13.856c1.54 0 2.502-1.667 1.732-3L13.732 4c-.77-1.333-2.694-1.333-3.464 0L3.34 16c-.77 1.333.192 3 1.732 3z' },
   { to: '/auth/settings',  label: 'Auth Settings', icon: 'M10.325 4.317c.426-1.756 2.924-1.756 3.35 0a1.724 1.724 0 002.573 1.066c1.543-.94 3.31.826 2.37 2.37a1.724 1.724 0 001.066 2.573c1.756.426 1.756 2.924 0 3.35a1.724 1.724 0 00-1.066 2.573c.94 1.543-.826 3.31-2.37 2.37a1.724 1.724 0 00-2.573 1.066c-.426 1.756-2.924 1.756-3.35 0a1.724 1.724 0 00-2.573-1.066c-1.543.94-3.31-.826-2.37-2.37a1.724 1.724 0 00-1.066-2.573c-1.756-.426-1.756-2.924 0-3.35a1.724 1.724 0 001.066-2.573c-.94-1.543.826-3.31 2.37-2.37.996.608 2.296.07 2.572-1.065z M15 12a3 3 0 11-6 0 3 3 0 016 0z' },
 ];