feat: add Help page with search, streamline copilot, misc UI fixes

Adds searchable Help/User Guide page, trims copilot tool bloat,
adds OTHER department option, and various form/layout improvements.

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

frontend/package.json

@@ -23,6 +23,7 @@
     "axios": "^1.6.5",
     "clsx": "^2.1.0",
     "date-fns": "^3.2.0",
+    "fuse.js": "^7.1.0",
     "leaflet": "^1.9.4",
     "lucide-react": "^0.309.0",
     "qrcode.react": "^4.2.0",