IM: Send ping message to existing group when re-selecting a session

[FridayLiu]

Problem

When a user re-selects an existing session in P2P chat (Feishu/DingTalk), the adapter tells the user "this session already has a group chat, please use that group" — but the group may have sunk to the bottom of the users chat list, making it hard to find.

Proposed Solution

For group-based IM adapters (Feishu & DingTalk), when a user selects an existing session that already has a bound group:

1. Send a short ping message to the existing group (e.g. "📌 Session activated — continue chatting here")
2. This causes the group to surface to the top of the users IM chat list
3. Optionally still send the P2P redirect hint

Affected Adapters

• electron/main/channels/feishu/feishu-adapter.ts — session selection flow (~line 1020-1072)
• electron/main/channels/dingtalk/dingtalk-adapter.ts — session selection flow (~line 725-773)
• Both check hasGroupForConversation() and currently only send a P2P text redirect

Not Affected

P2P-based adapters (Teams, Telegram, WeCom) handle session switching within the P2P chat directly — no group ping needed.

Implementation Notes

• Use existing transport.sendText(chatId, text) to ping the group
• Group chatId is available via sessionMapper.getGroupChatIdForConversation(conversationId)
• Keep message concise to avoid noise