chore: remove dead code and unused dependencies

Cleans up stale implementation artifacts:
- Delete legacy `src/webhook.ts` (dead code per AGENTS.md)
- Delete admin composables `useMe.ts` and `useRoutes.ts`
- Remove unused dependencies `jose` and `yaml`
- Remove stale `Me` interface, `FILTER_LABELS`, `invalidateConfigCache`, and formatter re-exports

docs/zh/contributing.md

@@ -20,7 +20,7 @@ src/
 ├── server.ts             # Hono 应用: /health、/webhook、/discord/interactions、/telegram/webhook，挂载 /auth、/admin + /
 ├── core/
 │   └── dispatch.ts       # 平台中立分发：匹配路由 → formatEvent → getDriver().send/edit
-├── events/               # GitHub webhook 事件流水线（旧 src/webhook.ts 为死代码）
+├── events/               # GitHub webhook 事件流水线：验证签名、解析事件、匹配路由
 │   ├── verify.ts         # HMAC 签名验证 (Web Crypto，时间安全)
 │   ├── parse.ts          # parseEvent (headers + body → WebhookEvent)
 │   └── match.ts          # matchRoute、eventOwners、extractBranch、关键词过滤

docs/zh/guide/introduction.md

@@ -43,7 +43,7 @@ GitHub Webhook → Cloudflare Worker (Hono)
 - **Telegram 投递**: Telegram Bot API（webhook 带可选 secret-token 校验）
 - **Web UI**: Nuxt 3 静态 SPA，由 Worker 资源托管
 - **存储**: Cloudflare KV + D1
-- **鉴权**: Web Crypto API (HMAC-SHA256、Ed25519)、octokit (GitHub API)、jose（依赖）
+- **鉴权**: Web Crypto API (HMAC-SHA256、Ed25519)、octokit (GitHub API)
 - **语言**: TypeScript
 
 ## 许可证