Phase 0 go-live polish: hands-off incremental sync + refresh action

- backend/ingest/sync_scheduler.py: periodic incremental-sync loop (every
  CRM_INGEST_SYNC_INTERVAL_MIN min); resilient, --once for testing.
- start9/0.4: "Refresh search index" action (incremental sync.py); entrypoint
  launches the scheduler as a background process when Spark/Qdrant are set;
  CRM_INGEST_SYNC_INTERVAL_MIN env; pre-release note on fastembed/mcp pins.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

start9/0.4/startos/actions/index.ts

@@ -1,4 +1,7 @@
 import { sdk } from '../sdk'
 import { buildSearchIndex } from './buildSearchIndex'
+import { refreshSearchIndex } from './refreshSearchIndex'
 
-export const actions = sdk.Actions.of().addAction(buildSearchIndex)
+export const actions = sdk.Actions.of()
+  .addAction(buildSearchIndex)
+  .addAction(refreshSearchIndex)