Introduces a `processing` state to the AI analysis lifecycle to prevent
duplicate processing of the same messages.
- Implements row-level locking using `FOR UPDATE SKIP LOCKED` in
`messageStore.ts` to ensure atomic message acquisition.
- Adds a `processing` status to the `AIStatus` type and database schema.
- Fixes a TOCTOU race condition in `aiAnalyzer.ts` by synchronizing
the conversation processing lock before async database operations.
- Implements `revertStuckProcessingMessages` to recover messages stuck
in the `processing` state due to worker crashes or timeouts.
- Updates `processBatch` and scheduling logic to correctly manage and
release conversation-level locks.
MythEclipse
09f6e80ddd