Teammate Message Submission Handler

What: New handler that allows submitting messages directly from the inbox to the conversation when idle.

How it works: Messages from teammates in the inbox can now be submitted as user queries when the session is idle, enabling seamless teammate collaboration.

Details:

• Added w39() hook at line 478948 for inbox polling and message delivery
• Added onSubmitTeammateMessage callback that creates a user message from teammate content
• Includes sophisticated idle detection and busy-state queuing logic
• Evidence: Hook usage at line 19883 in main component