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

bot/package.json

@@ -0,0 +1,21 @@
+{
+  "name": "@araharah/bot",
+  "private": true,
+  "type": "module",
+  "scripts": {
+    "test": "node test/runner.mjs",
+    "typecheck": "tsc --noEmit",
+    "dev": "wrangler dev",
+    "deploy": "wrangler deploy",
+    "commands": "node scripts/register-commands.mjs"
+  },
+  "dependencies": {
+    "grammy": "^1.46.0"
+  },
+  "devDependencies": {
+    "wrangler": "^4.151.3",
+    "typescript": "^5.9.3",
+    "@cloudflare/workers-types": "^5.20261022.1",
+    "@types/node": "^26.6.5"
+  }
+}