Refactor monolithic modules and harden booking, email, and auth infrastructure.

Split oversized frontend API client, email service, and admin/booking pages into focused modules while preserving import surfaces, and add Redis-backed queues, stale booking cleanup, stronger auth, and scale deployment configs.

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/package.json

@@ -22,8 +22,7 @@
     "react-dom": "^18.3.1",
     "react-hot-toast": "^2.4.1",
     "react-markdown": "^10.1.0",
-    "remark-gfm": "^4.0.1",
-    "swr": "^2.2.5"
+    "remark-gfm": "^4.0.1"
   },
   "devDependencies": {
     "@types/node": "^20.14.9",