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

package.json

@@ -6,7 +6,9 @@
   "license": "ISC",
   "private": true,
   "scripts": {
-    "test": "echo \"Error: no test specified\" && exit 1"
+    "test": "jest --ci --forceExit backend/__tests__/",
+    "test:backend": "jest --ci --forceExit backend/__tests__/",
+    "test:frontend": "cd frontend && CI=true npx react-scripts test --watchAll=false --ci --forceExit"
   },
   "keywords": [],
   "dependencies": {