Add CI/CD pipeline, feedback modal, Atlas qualys_id fallback, and health endpoint

- Rewrite .gitlab-ci.yml with proper stages, blocking tests, staging
  environment on dev box, and SSH-based production deploy to 71.85.90.6
- Add POST /api/health endpoint for pipeline verification
- Add POST /atlas/hosts/:hostId/refresh-cache for Atlas cache staleness
- AtlasSlideOutPanel: auto-resolve qualys_id from Atlas vulnerabilities,
  prefer qualys_id over active_host_findings_id, retry on failure
- Add FeedbackModal component with bug report button in header and
  feature request in UserMenu, creates GitLab issues via /api/feedback
- Fix all frontend test failures (ESM transforms, TextDecoder polyfill,
  fast-check resolution, App.test.js boilerplate replacement)
- Fix root package.json test script to run jest
- Add deploy/ directory with staging systemd service and setup script

backend/server.js

@@ -135,6 +135,11 @@ app.use('/uploads', express.static('uploads', {
     index: false
 }));
 
+// Health check endpoint (public — used by CI/CD pipeline verification)
+app.get('/api/health', (req, res) => {
+    res.json({ status: 'ok', timestamp: new Date().toISOString() });
+});
+
 // Auth routes (public)
 app.use('/api/auth', createAuthRouter(logAudit));