feat(02-01): bot workspace scaffold with Env contract (D-09/D-10/D-11/D-15)

- bot/ npm workspace sibling to theme/: grammy ^1.46.0, wrangler ^4.151.3, TS ^5.9.3
- src/config.ts exports Env (BOT_TOKEN, WEBHOOK_SECRET, chat_sessions KVNamespace)
- wrangler.jsonc: main src/webhook.ts + chat_sessions KV binding (id filled in plan 03)
- .gitignore ships .dev.vars/.wrangler/ in the same commit as .dev.vars.example (D-17)
- root delegate scripts bot:test/typecheck/dev/deploy/commands

package.json

@@ -3,13 +3,19 @@
   "private": true,
   "type": "module",
   "workspaces": [
-    "theme"
+    "theme",
+    "bot"
   ],
   "scripts": {
     "build": "npm run build --workspace theme",
     "sheet": "npm run sheet --workspace theme",
     "gallery": "npm run gallery --workspace theme",
     "audit": "npm run audit --workspace theme",
-    "capture": "npm run capture --workspace theme"
+    "capture": "npm run capture --workspace theme",
+    "bot:test": "npm test -w bot",
+    "bot:typecheck": "npm run typecheck -w bot",
+    "bot:dev": "npm run dev -w bot",
+    "bot:deploy": "npm run deploy -w bot",
+    "bot:commands": "npm run commands -w bot"
   }
 }