refactor: 将 weixin 模块从 src/ 迁移至 packages/weixin 工作区包

将 src/services/weixin/ 中的纯业务逻辑迁入 @claude-code-best/weixin
workspace 包，降低 src/ 耦合度。仅保留 server.ts 作为薄适配层。

- 迁移 7 个无修改的纯模块 (types/api/accounts/login/pairing/media/send)
- monitor.ts 内联 PERMISSION_REPLY_RE 正则，解除对 src/ 的依赖
- permissions.ts 本地定义 ChannelPermissionRequestParams 接口
- cli.ts 拆分：serve 子命令通过回调注入，login/access 保留在包内
- server.ts 重写为从 @claude-code-best/weixin 导入
- 新增 cli-serve.ts 作为 serve 入口薄壳

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tsconfig.json

@@ -19,7 +19,9 @@
             "@claude-code-best/mcp-client/*": ["./packages/mcp-client/src/*"],
             "@claude-code-best/mcp-client": ["./packages/mcp-client/src/index.ts"],
             "@claude-code-best/agent-tools/*": ["./packages/agent-tools/src/*"],
-            "@claude-code-best/agent-tools": ["./packages/agent-tools/src/index.ts"]
+            "@claude-code-best/agent-tools": ["./packages/agent-tools/src/index.ts"],
+            "@claude-code-best/weixin/*": ["./packages/weixin/src/*"],
+            "@claude-code-best/weixin": ["./packages/weixin/src/index.ts"]
         }
     },
     "include": ["src/**/*.ts", "src/**/*.tsx", "packages/**/*.ts", "packages/**/*.tsx"],