The internal Target model uses a plain bool for ProxyProtocol,
which was always serialized to the API response as false even
when not configured. Only set the API field when true so it
gets omitted via omitempty when unset.
The expose tracker used sync.Map for in-memory TTL tracking of active expose sessions, which broke and lost all sessions on restart.
Replace with SQL-backed operations that reuse the existing meta_last_renewed_at column:
- Add store methods: RenewEphemeralService, GetExpiredEphemeralServices, CountEphemeralServicesByPeer, EphemeralServiceExists
- Move duplicate/limit checks inside a transaction with row-level locking (SELECT ... FOR UPDATE) to prevent concurrent bypass
- Reaper re-checks expiry under row lock to avoid deleting a just-renewed service and prevent duplicate event emission
- Add composite index on (source, source_peer) for efficient queries
- Batch-limit and column-select the reaper query to avoid DB/GC spikes
- Filter out malformed rows with empty source_peer
