feat(auth): separate read and write bilibili accounts

tests/test_snapshot.py

@@ -75,9 +75,10 @@ def make_service(tmp, transport, *, track_fans=(37754047,), logger=None,
                  retries=3, cookie="SESSDATA=secret; buvid3=device"):
     path = Path(tmp) / "config.json"
     path.write_text(json.dumps({
-        "mid": 28802351,
-        "csrf": "csrf",
-        "cookie": cookie,
+        "bilibili": {
+            "read": {"mid": 28802351, "csrf": "csrf", "cookie": cookie},
+            "write": {"mid": 2, "csrf": "write-csrf", "cookie": "write-cookie"},
+        },
         "storage": {
             "database_path": str(Path(tmp) / "app.db"),
             "backup_dir": str(Path(tmp) / "backup"),