refactor(download-history): rename mark_not_downloaded to mark_as_deleted

The method mark_not_downloaded() was misleading — it doesn't negate
'downloaded' history (the model was indeed downloaded before), but
rather sets is_deleted_override = 1 to indicate the version was
downloaded and subsequently deleted. This flag allows re-download when
the 'skip previously downloaded' setting is enabled.

Rename to mark_as_deleted() to accurately reflect its semantics.

tests/routes/test_api_snapshots.py

@@ -79,7 +79,7 @@ class FakeDownloadHistoryService:
     async def mark_downloaded(self, *_args, **_kwargs):
         return None
 
-    async def mark_not_downloaded(self, *_args, **_kwargs):
+    async def mark_as_deleted(self, *_args, **_kwargs):
         return None
 
 

tests/routes/test_misc_routes.py

@@ -903,7 +903,7 @@ class FakeDownloadHistoryService:
             (model_type, version_id, model_id, source, file_path)
         )
 
-    async def mark_not_downloaded(self, model_type, version_id):
+    async def mark_as_deleted(self, model_type, version_id):
         self.marked_not_downloaded.append((model_type, version_id))