fix(auth): expose both id and userId in JWT validate result

backend/src/auth/jwt.strategy.ts

@@ -14,8 +14,15 @@ export class JwtStrategy extends PassportStrategy(Strategy) {
     });
   }
 
-  async validate(payload: { sub: number; username: string; role: string; isPremium: boolean }) {
-    this.logger.log(`Validating token for user ID: ${payload.sub}, Username: ${payload.username}`);
-    return { userId: payload.sub, username: payload.username, role: payload.role ?? 'user', isPremium: payload.isPremium ?? false };
+  async validate(payload: { sub?: number; id?: number; userId?: number; username?: string; role?: string; isPremium?: boolean }) {
+    const resolvedUserId = payload.sub ?? payload.id ?? payload.userId;
+    this.logger.log(`Validating token for user ID: ${resolvedUserId}, Username: ${payload.username}`);
+    return {
+      id: resolvedUserId,
+      userId: resolvedUserId,
+      username: payload.username,
+      role: payload.role ?? 'user',
+      isPremium: payload.isPremium ?? false,
+    };
   }
 }