feat(web): cache dashboard aggregations with version invalidation

reaction_board/services/snapshot.py

@@ -284,6 +284,11 @@ class SnapshotService:
 
         self._run_backup(cfg, stat_date, summary)
 
+        if summary.success or summary.removed or summary.failed:
+            self.repo.bump_cache_version("videos")
+        if summary.fans_ok or summary.fans_failed:
+            self.repo.bump_cache_version("fans")
+
         summary.finished_at = self._now()
         self._log(
             "info" if summary.completed else "warning",