Problem

When the gateway processes an inbound message, there is no way to know what state it is in — whether it was accepted, is currently being processed by the AI, was successfully delivered, or failed silently.

This makes it difficult to diagnose:

• "I sent a message but never got a reply" — was it accepted? Did the AI run? Did delivery fail?
• "The bot seems stuck" — is it actually generating, or did it silently error?
• Operators running multiple agents have no way to audit message flow across sessions

Current behavior

• Inbound messages are processed in-memory with no persistent state tracking
• If the gateway crashes mid-generation, there is no record the message was ever accepted
• Delivery failures are logged but not queryable after the fact
• openclaw channels status shows channel health but not per-message state

Expected behavior

Each inbound message turn should have a persistent lifecycle record tracking:

• When it was accepted
• Which agent/session is processing it
• Current status (accepted → running → delivered / aborted / failed)
• Final disposition with timestamp

This enables operators to answer "what happened to message X?" and build monitoring/alerting on message flow health.

Additional context

Related to #26764 — turn tracking is a prerequisite for reliable dedup since it provides a persistent record of which turns have already been processed.