fix(channels): handle bot p2p chat entered event in Feishu channel

[lysandre001]

Summary

• Register a handler for the im.chat.access_event.bot_p2p_chat_entered_v1 event to prevent "processor not found" errors when users first open a private chat with the Feishu bot
• Remove a redundant None check in FeishuChannel.send() error handling that was unreachable

Problem

When a user enters a bot's private chat in Feishu, the Feishu platform sends a bot_p2p_chat_entered_v1 event via the WebSocket connection. Since this event was not registered in the EventDispatcherHandler, the lark-oapi SDK logged an error on every bot entry:

[Lark] [ERROR] handle message failed, message_type: event, err: processor not found, type: im.chat.access_event.bot_p2p_chat_entered_v1

Fix

Added register_p2_im_chat_access_event_bot_p2p_chat_entered_v1(self._on_bot_chat_entered) to the event handler builder chain, with a simple logging handler that acknowledges the event without side effects.

Changes

File	Change
backend/app/channels/feishu.py	Register bot_p2p_chat_entered_v1 event handler + cleanup unreachable None check in send error path

Testing

• Verified Feishu WebSocket connects successfully without processor not found errors
• Confirmed Feishu channel started and ChannelService started with channels: ['feishu'] in gateway logs

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[WillemJiang]

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