Добавлена поддержка обмена играми с типом прохождения (playthrough)

- Обновлены схемы SwapCandidate и SwapRequestChallengeInfo для поддержки прохождений
- get_swap_candidates теперь возвращает и челленджи, и прохождения
- accept_swap_request теперь корректно меняет challenge_id, game_id, is_playthrough и bonus_assignments
- Обновлён UI для отображения прохождений в списке кандидатов и запросах обмена

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/app/schemas/event.py

@@ -128,10 +128,16 @@ class SwapCandidate(BaseModel):
     """Participant available for assignment swap"""
     participant_id: int
     user: UserPublic
-    challenge_title: str
-    challenge_description: str
-    challenge_points: int
-    challenge_difficulty: str
+    is_playthrough: bool = False
+    # Challenge fields (used when is_playthrough=False)
+    challenge_title: str | None = None
+    challenge_description: str | None = None
+    challenge_points: int | None = None
+    challenge_difficulty: str | None = None
+    # Playthrough fields (used when is_playthrough=True)
+    playthrough_description: str | None = None
+    playthrough_points: int | None = None
+    # Common field
     game_title: str
 
 
@@ -145,11 +151,17 @@ class SwapRequestCreate(BaseModel):
 
 
 class SwapRequestChallengeInfo(BaseModel):
-    """Challenge info for swap request display"""
-    title: str
-    description: str
-    points: int
-    difficulty: str
+    """Challenge or playthrough info for swap request display"""
+    is_playthrough: bool = False
+    # Challenge fields (used when is_playthrough=False)
+    title: str | None = None
+    description: str | None = None
+    points: int | None = None
+    difficulty: str | None = None
+    # Playthrough fields (used when is_playthrough=True)
+    playthrough_description: str | None = None
+    playthrough_points: int | None = None
+    # Common field
     game_title: str