test: fold the last Windows path and label assumptions

Second pass over the informational Windows job (91 failures -> 11 -> 0):

* `_identity`/`_fold` now wrap the assertions my first sweep skipped: the
  parenthesised and multi-line ones, and the ones whose token list was
  incomplete (`base_models_roots`, `embeddings_roots`).
* The reconciler's `current_name` and `active_roots` carry the drive-prefixed
  label on Windows ("C: loras"), so the last direct comparison goes through
  `_root_label_names` too.
* `open_settings_location` reveals the settings *file* with
  `explorer /select,` on Windows instead of opening the containing folder, so
  that test asserts the platform's call instead of the POSIX one.
* Three more expectations are written in the business form the code returns
  (metadata payload, extracted download paths, hydrated preview URL).

tests/services/test_download_manager_error.py

@@ -617,10 +617,10 @@ async def test_execute_download_extracts_zip_multiple_models(monkeypatch, tmp_pa
     assert dummy_scanner.add_model_to_cache.await_count == 2
 
     metadata_calls = MetadataManager.save_metadata.await_args_list
-    assert metadata_calls[0].args[0] == str(extracted_one)
+    assert metadata_calls[0].args[0] == str(extracted_one).replace(os.sep, "/")
     # SHA256 comes from metadata (API value), not recalculated
     assert metadata_calls[0].args[1].sha256 == "sha256"
-    assert metadata_calls[1].args[0] == str(extracted_two)
+    assert metadata_calls[1].args[0] == str(extracted_two).replace(os.sep, "/")
     assert metadata_calls[1].args[1].sha256 == "sha256"