feat(server): W2-A login gate, secrets, settings, instances, audit, engine panel API and PG-backed SSE bus

- Admin login gate (docs/design/auth-reference.md): admin_user/admin_session/login_attempt
  (migration 0015), one-time setup token logged once + conditional UPDATE, argon2id via
  hash-wasm (WASM; compiled binary has no --allow-ffi), sha256-stored sessions in HttpOnly
  SameSite=Lax cookie umt_session (fixed 12h TTL, soft revoke), HMAC-derived double-submit
  CSRF, IP (5) + account (15) failure limits per 15 min, password change revokes other
  sessions, optional TOTP with replay counter, AuditAction enum.
- Unified auth middleware: cookie session or Bearer API key -> c.var.actor
  {type: admin|api_key, id, name, scopes}; requireScope works for both; requireAdminSession.
- ctx.secrets: AES-256-GCM, per-secret HKDF-SHA256 key from SECRET_MASTER_KEY, AAD bound
  to (id, purpose); ctx.settings: 30s cache invalidated by settings.changed events.
- Endpoints: /auth/*, /settings, /api-keys, /secrets, /audit-events, library-roots,
  downloader/media-server instances (+test), path-mappings (+verify),
  PUT /sites/{id}/credentials, /engine/runs|stats|cancel (read-only openworkflow schema).
- SSE: PgEventBus (sse_event table, migration 0016, LISTEN/NOTIFY umt_events, catch-up by
  seq, pruning, resync); EventBusPort is now async.
- Tests: login/rate limit/revocation/CSRF/TOTP, secrets round trip and no log leakage,
  admin APIs against mock qB/Emby, SSE across two Deno subprocesses.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

deno.json

@@ -26,6 +26,7 @@
     "@xmldom/xmldom": "npm:@xmldom/[email protected]",
     "cheerio": "npm:[email protected]",
     "fast-xml-parser": "npm:[email protected]",
+    "hash-wasm": "npm:[email protected]",
     "hono": "npm:[email protected]",
     "hono/": "npm:/[email protected]/",
     "kysely": "npm:[email protected]",