fix(types): resolve pre-existing basedpyright errors in py/ and standalone.py

Fix ~950 basedpyright errors across the backend:
- Convert ineffective # type: ignore comments to # pyright: ignore[rule]
- Add missing generic type arguments (Dict[str, Any], list[Any], ...)
- Annotate dynamic dict literals and runtime-initialized attributes
- Widen CivitAI provider tuple signatures in recipe parsers
- Remove dead LoraRoutes handlers calling nonexistent LoraService methods
- Suppress unavoidable ServiceRegistry import cycles (basedpyright counts
  function-local imports as cycle edges)

py/services/preview_asset_service.py

@@ -22,7 +22,7 @@ class PreviewAssetService:
         self,
         *,
         metadata_manager,
-        downloader_factory: Callable[[], Awaitable],
+        downloader_factory: Callable[[], Awaitable[Any]],
         exif_utils,
     ) -> None:
         self._metadata_manager = metadata_manager
@@ -69,6 +69,8 @@ class PreviewAssetService:
         if not preview_url:
             return
 
+        preview_url = str(preview_url)
+
         def extension_from_url(url: str, fallback: str) -> str:
             try:
                 parsed = urlparse(url)