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

deploy/cve-backend-staging.service

@@ -0,0 +1,17 @@
+[Unit]
+Description=CVE Dashboard Backend - Staging (Express API on port 3100)
+After=network.target
+
+[Service]
+Type=simple
+WorkingDirectory=/home/cve-dashboard-staging/backend
+ExecStart=/usr/bin/node server.js
+Restart=on-failure
+RestartSec=5
+EnvironmentFile=/home/cve-dashboard-staging/backend/.env
+Environment=PORT=3100
+StandardOutput=append:/home/cve-dashboard-staging/backend/backend-staging.log
+StandardError=append:/home/cve-dashboard-staging/backend/backend-staging.log
+
+[Install]
+WantedBy=multi-user.target