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>

backend/package.json

@@ -13,6 +13,7 @@
     "db:import": "tsx src/db/import.ts"
   },
   "dependencies": {
+    "@aws-sdk/client-s3": "^3.1075.0",
     "@hono/node-server": "^1.11.4",
     "@hono/swagger-ui": "^0.4.0",
     "@hono/zod-openapi": "^0.14.4",
@@ -22,6 +23,7 @@
     "dotenv": "^17.2.3",
     "drizzle-orm": "^0.31.2",
     "hono": "^4.4.7",
+    "ioredis": "^5.11.1",
     "jose": "^5.4.0",
     "nanoid": "^5.0.7",
     "nodemailer": "^7.0.13",