Handles incoming messaging requests from Twilio for different message types. Supported message types are:

• assistant-request: Sets up the AI assistant for the call, initializes call data and cache, and returns assistant configuration
• status-update: Processes call status changes like call ending or forwarding
• end-of-call-report: Triggers background processing of call completion, including transcripts, recordings, and post-call actions

This endpoint receives webhook requests from Twilio to handle various stages of call processing.