Phase 3 infrastructure hardening: IP/UA binding, nginx getallheaders fallback, auth rate limiting, permission cache

Phase 2 session stability: refresh queue, Bearer fallback, proactive refresh

Phase 1 auth security hotfixes: cookie-based session, bearer checks, router guard sync ...

- Remove access_token from OAuth callback URL (token leak fix)
- Add sanitizeReturnTo() to prevent open redirect on login/callback
- Add Bearer token expiration check in resolve_user_by_bearer()
- Add user status check in load_user_by_id() (block inactive/banned)
- Cache authStore.init() promise to prevent race condition
- Await auth init in router beforeEach guard
- Remove URL token parsing from main.js and LoginPage
- Remove hasTokenInUrl workaround from client.js 401 handler

Fix OAuth callback URL: insert access_token query string BEFORE hash fragment so Vue can read it via window.location.search

Add Bearer token persistence for cross-domain SPA auth ...

- api/auth.js: persist access token in localStorage so it survives
  page reloads and works across domains (panel vs server IP).
- LoginPage.vue: on mount, check for access_token in URL query
  params (from OAuth callback) and initialize auth store.
- AuthController::callback(): append access_token + expires_in to
  the redirect URL so the SPA can capture it.

Fix logout: session_start + destroy cookie + redirect to local /login instead of /auth/login

Make user card avatar/name clickable link to gnexus-auth profile

Add GnUserCard drawer footer; fix proxy.php cookie forwarding and /auth/ whitelist

Fix auth session persistence: add credentials:include to fetch and session_start to auth flow ...

- http.js: add credentials: 'include' to fetch() so cookies are sent
  with every API request (fixes /auth/me returning 401 after callback)
- AuthControllerTrait::resolve_user(): ensure session_start() before
  reading
- AuthController::callback(): ensure session_start() before writing

- AuthService::handleCallback(): defer DB token persistence until
  local user ID is resolved; store temp token data in session
- UserResolver: fix lastInsertId() method name, remove avatarUrl()
  call (use profile array instead)

This fixes the loop where user was redirected back to /login after
successful OAuth callback because PHP session cookie was not sent
with the /auth/me request.

Phase 0: gnexus-auth integration infrastructure ...

- Add gnexus/auth-client via Composer vcs
- Thin PSR-18/17 cURL adapter (zero extra deps)
- SessionStateStore, SessionPkceStore, DbTokenStore
- AuthService wrapper: login URL, callback, logout, refresh, me
- UserResolver + PermissionResolver
- AuthController (login, callback, logout, me, refresh)
- WebhookController + WebhookRouter + event handlers
- AuthControllerTrait for endpoint protection
- Migration: 9 tables (users, roles, permissions, overrides, groups, members, group_perms, sessions, audit) + seed data
- Remove old Example_AuthController
- Add GAUTH_* env variables to config and .env.example