feat: implement multi-channel Feishu Bot settings UI and WebSocket hot reload

[skloxo]

Summary (概述)

This PR introduces multi-channel Feishu (Lark) Bot settings UI and implements WebSocket connection isolation with hot-reloading. It also resolves critical event loop conflicts in the Lark SDK when running multiple connections concurrently or reloading.
此 PR 实现了多通道飞书（Lark）机器人的可视化配置与热重载，并通过对 Lark SDK WebSocket 模块的动态属性代理，解决了多连接或热重载时因共享主线程 Uvicorn 事件循环引发的 RuntimeError 和死锁冲突。

Key Changes (主要修改)

1. Multi-channel Configurations & Visualized UI

   • Implemented a unified backend configuration storage (feishu_channels.json) and CRUD API endpoints (/settings/platforms/feishu/channels).
   • Redesigned the Settings UI with Feishu channels CRUD capability, cards layout, and an easy toggle.
   • 实现了多通道的持久化存储以及 CRUD API 端点；在前端 Settings 页重构了可视化管理卡片和开关。

2. Event Loop Isolation via Thread-local LoopProxy (Critical Fix)

   • Patched lark_oapi.ws.client.loop using a thread-local proxy class. When Lark SDK accesses the loop, it dynamically routes to the dedicated event loop running in its isolated background Thread.
   • This resolves Uvicorn/uvloop conflicts (RuntimeError: Event loop is already running) when launching or restarting multiple WS connections.
   • 通过对 Lark SDK 全局 WebSocket 模块的 loop 变量注入 LoopProxy 动态代理，将每个飞书机器人的长连接隔离在专属的后台线程与事件循环中，彻底解决了多通道热重载与并发时引发的 RuntimeError。

3. User-friendly OpenID Reflection Command & UX

   • Allows users to retrieve their Feishu OpenID by sending /myid to the Bot even when they are not whitelisted yet.
   • Dynamically folds/unfolds the "Allowed Users" whitelist inputs based on the public debug mode checkbox, alongside safety warnings.
   • 在未配置白名单时，允许用户通过向 Bot 发送 /myid 反射获取自己的 OpenID，解决初始化配置的死锁；优化了白名单输入框的自动折叠与安全提示横幅。

Verification (验证情况)

• Backend platform tests (agent/tests/test_platform_base.py) run successfully and coverage passes.
• Verified in local container that multiple Feishu bots concurrently process commands (/myid, /goal, etc.) stably with instant UI toggling and live reload.
• 后端平台测试与前端 UI 单元测试均已通过；在容器开发环境中验证通过，多个 Bot 可稳定独立响应飞书指令。

[warren618]

Thanks for the PR — we’ve seen it and will review as soon as we can.

Since this touches settings UI and hot reload behavior, we’ll check the backend/frontend contract, i18n coverage, and whether the first PR keeps the messaging/settings scope clean.