feat: Hammer Dashboard with sidebar navigation (HQ-21)

- Add React Router with sidebar layout (DashboardLayout)
- Queue is now a routed page at /queue
- Chat placeholder page at /chat
- Admin page accessible from sidebar
- Dark sidebar with amber accent for active nav
- Updated CORS and auth to support dash.donovankelly.xyz
- Renamed to Hammer Dashboard

frontend/package.json

@@ -14,6 +14,7 @@
     "better-auth": "^1.4.17",
     "react": "^19.2.0",
     "react-dom": "^19.2.0",
+    "react-router-dom": "^7.13.0",
     "tailwindcss": "^4.1.18"
   },
   "devDependencies": {