feat: Add challenge invitations fields and fix feed hasFollowing query

- Add invitations query fields with invitee data to GetChallenge
- Add participantCount field to GetChallenge
- Add GetMyChallengeEntries query (was missing)
- Add hasFollowing to GetVideoFeed response (fixes feed ordering)
- Sync schema with backend challenge types

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

src/operations/challenges.gql

@@ -39,6 +39,7 @@ query GetChallenge($id: ID!) {
     requiredPocketSize
     isPublic
     maxAttempts
+    participantCount
     ruleSet {
       id
       name
@@ -49,6 +50,21 @@ query GetChallenge($id: ID!) {
       username
       profileImageUri
     }
+    invitations {
+      id
+      status
+      createdAt
+      invitee {
+        id
+        username
+        profileImageUri
+      }
+      inviter {
+        id
+        username
+        profileImageUri
+      }
+    }
   }
 }
 
@@ -106,6 +122,25 @@ query GetMyChallengeInvitations {
   }
 }
 
+query GetMyChallengeEntries {
+  myChallengeEntries {
+    id
+    status
+    shotsCount
+    makesCount
+    makeRate
+    qualified
+    createdAt
+    challenge {
+      id
+      name
+    }
+    video {
+      id
+    }
+  }
+}
+
 mutation CreateRuleSet($name: String!, $description: String) {
   createRuleSet(name: $name, description: $description) {
     id