Add GraphQL queries and mutations for challenge feature

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

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

src/index.tsx

@@ -2577,6 +2577,7 @@ export enum NotificationTypeEnum {
   CommentReply = "COMMENT_REPLY",
   Follow = "FOLLOW",
   Reaction = "REACTION",
+  ChallengeInvite = "CHALLENGE_INVITE",
 }
 
 export type OtherErrorNeedsNote = {
@@ -4202,6 +4203,7 @@ export type GetVideoFeedQuery = {
       hasNextPage: boolean;
       endCursor?: string | null;
     };
+    hasFollowing?: boolean | null;
   };
 };
 
@@ -4492,6 +4494,8 @@ export type NotificationFragment = {
   id: number;
   notificationType: NotificationTypeEnum;
   videoId?: number | null;
+  challengeId?: number | null;
+  challenge?: { __typename?: "Challenge"; name: string } | null;
   reactionType?: string | null;
   isRead: boolean;
   createdAt: any;