Add playerSummaries to schema + Video fragments

Backs the multi-player vs UI: feed cards and the detail page both
read `video.playerSummaries`, a per-cluster rollup with username,
profile image, representative full-frame URL, makes/total/percentage.

  - PlayerSummaryFields fragment in shooter.gql
  - VideoCardFields (feed) and GetVideoDetails (detail) include
    playerSummaries via the new fragment
  - VideoCardFields tag selection extended to include tagClasses,
    needed for the FE's player_count detection

Generated by `just gql` from the BE additions in railbird PR
dean/video-player-summaries.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/operations/video.gql

@@ -83,6 +83,9 @@ query GetVideoDetails($videoId: Int!) {
       }
       name
     }
+    playerSummaries {
+      ...PlayerSummaryFields
+    }
   }
 }