fix(parcel-sync): allow DB download regardless of layer freshness

The top export buttons required all primary layers to be "fresh" (<7 days)
before using the DB download path. When stale, they fell through to live
eTerra sync which requires credentials — blocking users who just want to
download existing data. Now any UAT with data in DB uses the local export
path directly.

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

src/modules/parcel-sync/components/tabs/export-tab.tsx

@@ -149,10 +149,8 @@ export function ExportTab({
   const primaryLayers = dbLayersSummary.filter((l) =>
     PRIMARY_LAYERS.includes(l.id),
   );
-  const allFresh =
-    primaryLayers.length > 0 && primaryLayers.every((l) => l.isFresh);
   const hasData = dbTotalFeatures > 0;
-  const canExportLocal = allFresh && hasData;
+  const canExportLocal = hasData;
 
   const oldestSyncDate = primaryLayers.reduce(
     (oldest, l) => {