fix: NCWF-2 bugs and desing fixes (#7)

Co-authored-by: Lala, Shahd <Shahd.Lala@sybit.de>
Reviewed-on: #7

src/app/services/challenge-event.service.ts

@@ -61,4 +61,18 @@ export class ChallengeEventService {
     removeChallenge(challengeId: string): void {
         this.onChallengeRemoved(challengeId);
     }
+
+    /**
+     * Replace the full incoming list (used by HTTP polling)
+     */
+    setIncomingChallenges(challenges: Challenge[]): void {
+        this.incomingChallenges$.next(challenges);
+    }
+
+    /**
+     * Clear all incoming challenges (used on logout)
+     */
+    clear(): void {
+        this.incomingChallenges$.next([]);
+    }
 }