[Feishu] assistantMsg.content.flatMap is not a function error

[bk1man]

  ## Environment
  - Platform: Feishu (飞书)
  - OPENAEON Version: 2026.3.1
  - Model: MiniMax-M2.5

  ## Description
  When using Feishu session, the error `assistantMsg.content.flatMap is not a function` appears
randomly.

  ## Steps to Reproduce
  1. Start a Feishu session
  2. Have a conversation for a while
  3. Error occurs intermittently

  ## Expected Behavior
  Should handle all message content formats properly

  ## Additional Context
  - This error happens in Feishu sessions specifically
  - Possibly related to how Feishu message content is parsed (string vs array format)

[openaeon]

  ## Environment
  - Platform: Feishu (飞书)
  - OPENAEON Version: 2026.3.1
  - Model: MiniMax-M2.5

  ## Description
  When using Feishu session, the error `assistantMsg.content.flatMap is not a function` appears
randomly.

  ## Steps to Reproduce
  1. Start a Feishu session
  2. Have a conversation for a while
  3. Error occurs intermittently

  ## Expected Behavior
  Should handle all message content formats properly

  ## Additional Context
  - This error happens in Feishu sessions specifically
  - Possibly related to how Feishu message content is parsed (string vs array format)

This issue has been fixed.