Fix test: update challenge_user without setting completed

The completion validation now blocks completed=true without a
submission. Updated test to only set joined_discord, which doesn't
require a submission.

Author: icaroharry

tests/Feature/ChallengeSubmissionTest.php

@@ -164,8 +164,8 @@ public function it_can_update_challenge_user_data(): void
             'Authorization' => "Bearer $token",
         ]);
 
+        // Update non-completion fields (joined_discord)
         $response = $this->putJson("/api/challenges/{$challenge->slug}", [
-            'completed' => true,
             'joined_discord' => true,
         ], [
             'Authorization' => "Bearer $token",
@@ -177,7 +177,6 @@ public function it_can_update_challenge_user_data(): void
         $this->assertDatabaseHas('challenge_user', [
             'user_id' => $user->id,
             'challenge_id' => $challenge->id,
-            'completed' => true,
             'joined_discord' => true,
         ]);
     }