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.

tests/test_bilibili_client.py

@@ -361,6 +361,42 @@ def test_check_login_without_cookie_makes_no_request():
     assert transport.calls == []
 
 
+def test_missing_data_is_protocol_error():
+    for payload in (
+        {"code": 0, "message": "OK"},
+        {"code": 0, "message": "OK", "data": None},
+    ):
+        transport = QueueTransport([http_json(payload)])
+        client, _ = make_client(transport)
+        try:
+            client.fav_ids(1)
+        except BilibiliProtocolError as exc:
+            assert "data" in str(exc)
+        else:
+            raise AssertionError(f"ids 缺少 data 应报协议错误: {payload}")
+
+        transport = QueueTransport([http_json(payload)])
+        client, _ = make_client(transport)
+        try:
+            client.fav_infos(1, [123])
+        except BilibiliProtocolError as exc:
+            assert "data" in str(exc)
+        else:
+            raise AssertionError(f"infos 缺少 data 应报协议错误: {payload}")
+
+
+def test_empty_data_list_is_valid():
+    transport = QueueTransport([http_json({"code": 0, "message": "OK", "data": []})])
+    client, _ = make_client(transport)
+    assert client.fav_ids(4413147139) == []
+
+    transport = QueueTransport([http_json({"code": 0, "message": "OK", "data": []})])
+    client, _ = make_client(transport)
+    result = client.fav_infos(1, [123, 456])
+    assert result.items == {}
+    assert result.missing == (123, 456)
+
+
 def main():
     test_fav_ids_parse_and_anonymous_header()
     test_anonymous_failure_falls_back_to_full_cookie()
@@ -380,6 +416,8 @@ def main():
     test_relation_stat()
     test_check_login()
     test_check_login_without_cookie_makes_no_request()
+    test_missing_data_is_protocol_error()
+    test_empty_data_list_is_valid()
     print("OK: B 站只读客户端契约与重试测试全部通过")