feat(auth): authentication module with multi-tenant isolation (RFC-001)

Introduce an always-on auth layer with auto-created admin on first boot,
multi-tenant isolation for threads/stores, and a full setup/login flow.

Backend
- JWT access tokens with `ver` field for stale-token rejection; bump on
  password/email change
- Password hashing, HttpOnly+Secure cookies (Secure derived from request
  scheme at runtime)
- CSRF middleware covering both REST and LangGraph routes
- IP-based login rate limiting (5 attempts / 5-min lockout) with bounded
  dict growth and X-Forwarded-For bypass fix
- Multi-worker-safe admin auto-creation (single DB write, WAL once)
- needs_setup + token_version on User model; SQLite schema migration
- Thread/store isolation by owner; orphan thread migration on first admin
  registration
- thread_id validated as UUID to prevent log injection
- CLI tool to reset admin password
- Decorator-based authz module extracted from auth core

Frontend
- Login and setup pages with SSR guard for needs_setup flow
- Account settings page (change password / email)
- AuthProvider + route guards; skips redirect when no users registered
- i18n (en-US / zh-CN) for auth surfaces
- Typed auth API client; parseAuthError unwraps FastAPI detail envelope

Infra & tooling
- Unified `serve.sh` with gateway mode + auto dep install
- Public PyPI uv.toml pin for CI compatibility
- Regenerated uv.lock with public index

Tests
- HTTP vs HTTPS cookie security tests
- Auth middleware, rate limiter, CSRF, setup flow coverage

.env.example

@@ -6,6 +6,11 @@ JINA_API_KEY=your-jina-api-key
 
 # InfoQuest API Key
 INFOQUEST_API_KEY=your-infoquest-api-key
+# Authentication — JWT secret for session signing
+# If not set, an ephemeral secret is auto-generated (sessions lost on restart)
+# Generate with: python -c "import secrets; print(secrets.token_urlsafe(32))"
+# AUTH_JWT_SECRET=your-secure-jwt-secret-here
+
 # CORS Origins (comma-separated) - e.g., http://localhost:3000,http://localhost:3001
 # CORS_ORIGINS=http://localhost:3000
 
@@ -32,3 +37,5 @@ INFOQUEST_API_KEY=your-infoquest-api-key
 
 # GitHub API Token
 # GITHUB_TOKEN=your-github-token
+# WECOM_BOT_ID=your-wecom-bot-id
+# WECOM_BOT_SECRET=your-wecom-bot-secret