fix: close data integrity and hot-reload review findings

Backfill same-day snapshots for newly added or restored videos, preserve successful fan snapshots on resume, persist incomplete state before forced re-runs, and split collection completion from backup completion so failed backups can retry without API calls. Reject missing data payloads instead of treating them as empty folders, guard against mass-unfav on suspicious empty remote folders, rebuild Bilibili clients when credentials change, recompute primary folder ownership from active relations with per-folder fav_time, preserve original titles for dropped invalid videos, poll config every 60 seconds, and fix favsort verify interval and mixed resource types.

reaction_board/migrations.py

@@ -167,6 +167,13 @@ MIGRATIONS: tuple[Migration, ...] = (
             """,
         ),
     ),
+    Migration(
+        version=2,
+        name="folder_resource fav_time",
+        statements=(
+            "ALTER TABLE folder_resource ADD COLUMN fav_time INTEGER",
+        ),
+    ),
 )