Edge ↔ cloud sync state, last export bundle, and migration receipts for this self-host install.
Entities pending, in conflict, and cleanly synced. Backed by the
SyncEngine store (PostgresSyncStateStore for self-host installs configured with
SYNC_STATE_DB_URL; in-memory fallback otherwise).
/api/v1/admin/observability/summary
(slice #4437);
export-bundle metadata comes from /api/v1/admin/export/bundle when
#4425
ships; migration receipts come from /api/v1/admin/migration/last when
#4430
ships. Missing endpoints surface inline as "Not yet available — pending #N" instead of crashing.