Sync docs and fix flaky renewal e2e test

- ARCHITECTURE.md: add Vault Endpoints section, /unseal UI page,
  vault_sealed/vault_unsealed audit events, sealed interceptor in
  gRPC chain
- openapi.yaml: add /v1/vault/{status,unseal,seal} endpoints, update
  /v1/health sealed-state docs, add VaultSealed response component,
  add vault audit event types and Admin — Vault tag
- web/static/openapi.yaml: kept in sync with root
- test/e2e: increase renewal test token lifetime from 2s to 10s
  (sleep 6s) to eliminate race between token expiry and HTTP round-trip

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

ARCHITECTURE.md

@@ -431,11 +431,23 @@ All endpoints use JSON request/response bodies. All responses include a
 |---|---|---|---|
 | GET | `/v1/audit` | admin JWT | List audit log events |
 
+### Vault Endpoints
+
+| Method | Path | Auth required | Description |
+|---|---|---|---|
+| GET | `/v1/vault/status` | none | Returns `{"sealed": bool}`; always accessible |
+| POST | `/v1/vault/unseal` | none | Accept passphrase, derive key, unseal (rate-limited 3/s burst 5) |
+| POST | `/v1/vault/seal` | admin JWT | Zero key material and seal the vault; invalidates all JWTs |
+
+When the vault is sealed, all endpoints except health, vault status, and unseal
+return 503 with `{"error":"vault is sealed","code":"vault_sealed"}`. The UI
+redirects non-exempt paths to `/unseal`.
+
 ### Admin / Server Endpoints
 
 | Method | Path | Auth required | Description |
 |---|---|---|---|
-| GET | `/v1/health` | none | Health check |
+| GET | `/v1/health` | none | Health check — returns `{"status":"ok"}` or `{"status":"sealed"}` |
 | GET | `/v1/keys/public` | none | Ed25519 public key (JWK format) |
 
 ### Web Management UI
@@ -458,6 +470,7 @@ cookie pattern (`mcias_csrf`).
 
 | Path | Description |
 |---|---|
+| `/unseal` | Passphrase form to unseal the vault; shown for all paths when sealed |
 | `/login` | Username/password login with optional TOTP step |
 | `/` | Dashboard (account summary) |
 | `/accounts` | Account list |
@@ -797,6 +810,8 @@ The `cmd/` packages are thin wrappers that wire dependencies and call into
 | `policy_rule_updated` | Policy rule updated (priority, enabled, description) |
 | `policy_rule_deleted` | Policy rule deleted |
 | `policy_deny` | Policy engine denied a request (logged for every explicit deny) |
+| `vault_unsealed` | Vault unsealed via REST API or web UI; details include `source` (api\|ui) and `ip` |
+| `vault_sealed` | Vault sealed via REST API; details include actor ID, `source`, and `ip` |
 
 ---
 
@@ -1010,9 +1025,12 @@ details.
 ### Interceptor Chain
 
 ```
-[Request Logger] → [Auth Interceptor] → [Rate Limiter] → [Handler]
+[Sealed Interceptor] → [Request Logger] → [Auth Interceptor] → [Rate Limiter] → [Handler]
 ```
 
+- **Sealed Interceptor**: first in chain; blocks all RPCs with
+  `codes.Unavailable` ("vault sealed") when the vault is sealed, except
+  `AdminService/Health` which returns the sealed status.
 - **Request Logger**: logs method, peer IP, status code, duration; never logs
   the `authorization` metadata value.
 - **Auth Interceptor**: validates Bearer JWT, injects claims. Public RPCs