feat: operational status endpoint + reconciler/peer state tracking 📊

- ReconciliationWorker._last_run stores per-pass stats (da_servers_polled,
  zones_in_da/db, orphans_found/queued, hostnames_backfilled/migrated,
  zones_healed, duration_seconds, dry_run flag)
- ReconciliationWorker.get_status() exposes state for API/UI consumption
- _heal_backends() now returns healed count
- PeerSyncWorker.get_peer_status() serialises _peer_health to JSON-safe dict
  (url, healthy, consecutive_failures, last_seen) with summary totals
- WorkerManager tracks dead-letter count; queue_status() now returns nested
  reconciler/peer_sync dicts replacing flat reconciler_alive/peer_syncer_alive
- New GET /status endpoint (StatusAPI) aggregates queue depths, worker liveness,
  reconciler last-run, peer health, and live zone count; computes ok/degraded/error
- .gitignore: exclude .claude/, .vscode/, .env (always local)
- app.yml: add documented datastore section (SQLite default + MySQL commented)
- 164 tests passing (23 new tests added)

.gitignore

@@ -26,3 +26,9 @@ build
 *.mypy_cache
 *.pytest_cache
 /data/*
+
+# Editor / tool settings — always local, never committed
+.vscode/
+.claude/
+.env
+*.env