feat(01-21): add guarded Google sync progress

- persist one bounded owner-scoped current-run envelope
- reject stale writers and materialize interrupted runs safely

prisma/migrations/0287_google_health_sync_progress/migration.sql

@@ -0,0 +1,2 @@
+ALTER TABLE "google_health_connections"
+ADD COLUMN "sync_progress" JSONB;

prisma/schema.prisma

@@ -3857,6 +3857,9 @@ model GoogleHealthConnection {
   /// pre-fix externalId (a re-scored night minted parallel copies). Null =
   /// repair pending (or the connection predates the fix).
   sleepRepairedAt     DateTime? @map("sleep_repaired_at")
+  /// One bounded, owner-scoped current sync run. This is replaced at the start
+  /// of every run and never retains provider payloads or historical runs.
+  syncProgress        Json?     @map("sync_progress")
   createdAt           DateTime  @default(now()) @map("created_at")
   updatedAt           DateTime  @updatedAt @map("updated_at")