security: trust proxy fix, login rate limiting, default secret banners (#33)

* fix(security): default-secret banners, login rate limiting, real-IP passthrough

- app.set('trust proxy', 1) so req.ip resolves to real client IP behind nginx
- loginRateLimit() middleware on POST /api/auth/login; limits read from
  app_settings (login_rate_limit_max / login_rate_limit_window_sec) with
  60-second cache; falls back to 10/60s when Redis/DB unavailable
- GET /api/auth/security-status returns warnings for default JWT_SECRET,
  ENCRYPTION_KEY, and admin/admin credential — non-breaking for dev
- SecurityBanners component in AppLayout: yellow banner for default secrets,
  red banner + change-password link for default admin password
- Login rate limit settings exposed in Settings > General tab

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

* fix(security): rate-limit /security-status, suppress CodeQL false positive on /login

- Add allMethods option to rateLimitRedis so it can apply to GET routes
- Apply rateLimitRedis (10 req/60s per user) to GET /auth/security-status
  to prevent bcrypt-based CPU exhaustion by authenticated users
- Add lgtm suppression comment on POST /login — CodeQL does not recognize
  our custom loginRateLimit() middleware; rate limiting is in place

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

---------

Co-authored-by: Denis Evers <git@evers.sh>
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/src/index.ts

@@ -45,6 +45,8 @@ import networkServicesRoutes from './routes/networkServices';
 import credentialPresetsRoutes from './routes/credentialPresets';
 
 const app = express();
+// nginx sits exactly one hop in front; trust its X-Forwarded-For so req.ip is the real client IP
+app.set('trust proxy', 1);
 const httpServer = createServer(app);
 const PORT = parseInt(process.env.PORT || '3001', 10);