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/config.py

@@ -478,6 +478,7 @@ class ConfigStore:
         self._config = load_config(path, env=env, require_auth=require_auth)
         self._mtime_ns = self._read_mtime_ns()
         self.last_error: str | None = None
+        self.revision = 0
 
     def _read_mtime_ns(self) -> int | None:
         try:
@@ -499,4 +500,5 @@ class ConfigStore:
                 self.last_error = str(exc)
                 return self._config
             self.last_error = None
+            self.revision += 1
             return self._config