fix(memory): file the cache-hit result before running its callback

Restores the original ordering. Releasing the payload after the callback
meant filing the result after it too, so a callback that queried
get_result() or is_request_complete() for its own request would not have
found it -- a behaviour change unrelated to the memory fix.

The dict holds a reference to the same object, so releasing after filing
still clears the payload.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/background_data_service.py

@@ -199,6 +199,12 @@ class BackgroundDataService:
                     cached=True,
                     fetch_time=0.0
                 )
+                # Filed before the callback runs, as it always was: a callback
+                # that queries get_result()/is_request_complete() for its own
+                # request must still find it. Releasing afterwards mutates the
+                # same object the dict holds.
+                self.completed_requests[request_id] = result
+
                 if callback:
                     try:
                         callback(result)
@@ -206,8 +212,6 @@ class BackgroundDataService:
                         logger.error(f"Error in callback for request {request_id}: {e}")
                     self._release_payload(result)
 
-                self.completed_requests[request_id] = result
-
                 logger.debug(f"Cache hit for {sport} {year} data")
                 return request_id