TelemetryStore opened SQLite without WAL, so concurrent readers (server, aggregator, dashboard) hitting the database under inference load raised SQLITE_BUSY, and every insert committed immediately, paying fsync on each record.
- Enable PRAGMA journal_mode=WAL with synchronous=NORMAL and busy_timeout=5000, matching TraceStore.
- Batch inserts in memory under a lock and flush via executemany() when a batch reaches batch_size (default 50), when a batch goes stale, on any read through the store, and on close().
- Run a background flusher thread (default 5s interval) so a partial batch written just before traffic stops still becomes visible to other connections; close() stops the thread with an ordering that prevents touching a closed connection.
- Tests cover batching deferral, read-triggered flushes, stale-batch flushes, and close() behavior.
Fixes#560
Co-authored-by: Elliot Slusky <elliot@slusky.com>
