Fix season resolution crash and sanitize API exception leaks

- resolve_or_create_season now guards against non-dict season metadata
  instead of raising AttributeError when a provider returns a malformed
  payload (fixes the root cause behind #957)
- Sanitize the ~40 remaining "errors": str(e) sites in api/views.py that
  leaked raw exception text to API clients, matching the pattern already
  used for the episode watch/drop routes; exceptions are now logged
  server-side via logger.exception instead

Fixes #957

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

Author: dannyvfilms

src/api/tests/test_media_core.py

@@ -933,7 +933,8 @@ def test_media_detail_get_provider_failure_remains_internal_server_error(
         )
 
         self.assertEqual(response.status_code, 500)
-        self.assertEqual(response.data["errors"], "boom")
+        self.assertNotIn("errors", response.data)
+        self.assertNotIn("boom", response.data["detail"])
 
     @patch("api.views._queue_game_lengths_refresh", return_value=True)
     @patch("api.views.services.get_media_metadata")