refactor: migrate HTTP routing to Hono framework

- Add hono dependency
- Replace if/else routing chain with Hono app
- Convert all HTTP routes to Hono format:
  - GET /health, /setup-webhook, /webhook-info
  - POST /webhook
  - ALL /api/*
  - GET /
- Keep email, scheduled, queue handlers unchanged
- Maintain 100% backward compatibility

Benefits:
- Cleaner declarative routing
- Type-safe Env bindings
- Ready for future middleware (CORS, rate limiting)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

package-lock.json

@@ -8,6 +8,7 @@
       "name": "telegram-summary-bot",
       "version": "1.0.0",
       "dependencies": {
+        "hono": "^4.11.7",
         "zod": "^4.3.5"
       },
       "devDependencies": {
@@ -2625,6 +2626,15 @@
         "node": ">= 0.4"
       }
     },
+    "node_modules/hono": {
+      "version": "4.11.7",
+      "resolved": "https://registry.npmjs.org/hono/-/hono-4.11.7.tgz",
+      "integrity": "sha512-l7qMiNee7t82bH3SeyUCt9UF15EVmaBvsppY2zQtrbIhl/yzBTny+YUxsVjSjQ6gaqaeVtZmGocom8TzBlA4Yw==",
+      "license": "MIT",
+      "engines": {
+        "node": ">=16.9.0"
+      }
+    },
     "node_modules/html-escaper": {
       "version": "2.0.2",
       "resolved": "https://registry.npmjs.org/html-escaper/-/html-escaper-2.0.2.tgz",