fix(parcel-sync): safety check prevents mass deletion on stale remote data

If >80% of local features would be deleted (and >100 exist), skip deletion
and log a warning. This protects against session expiry returning empty
remote results, which previously caused the sync to mark ALL local
features as "removed" and attempt to delete them.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/modules/parcel-sync/services/sync-service.ts

@@ -319,7 +319,15 @@ export async function syncLayer(
     }
 
     // Mark removed features (batch to avoid PostgreSQL 32767 bind variable limit)
-    if (removedObjIds.length > 0) {
+    // Safety: if remote returned very few features compared to local, the session
+    // likely expired mid-sync — skip deletion to avoid wiping valid data.
+    const removedRatio = localObjIds.size > 0 ? removedObjIds.length / localObjIds.size : 0;
+    if (removedObjIds.length > 0 && removedRatio > 0.8 && localObjIds.size > 100) {
+      console.warn(
+        `[sync] SKIP delete: ${removedObjIds.length}/${localObjIds.size} features (${Math.round(removedRatio * 100)}%) ` +
+        `would be removed for ${layerId}/${siruta} — likely stale remote data. Aborting deletion.`,
+      );
+    } else if (removedObjIds.length > 0) {
       push({ phase: "Marcare șterse" });
       const BATCH = 30_000;
       for (let i = 0; i < removedObjIds.length; i += BATCH) {