Add username + profileImageUri to PlayerClusterGQL

The labeling UI was falling back to "user N" for any assigned cluster
whose user wasn't the video owner — e.g. an admin re-labels a video
they don't own. With the resolver now resolving usernames for every
confirmed cluster, the FE can render real names regardless of who's
viewing.

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

src/operations/shooter.gql

@@ -30,6 +30,8 @@ fragment PlayerClusterFields on PlayerClusterGQL {
   clusterId
   nShots
   userId
+  username
+  profileImageUri
   confirmed
   score
   shots {

src/schema.gql

@@ -882,6 +882,8 @@ type PlayerClusterGQL {
   clusterId: Int!
   nShots: Int!
   userId: Int
+  username: String
+  profileImageUri: String
   confirmed: Boolean!
   score: Int
   shots: [PlayerClusterShotGQL!]!