refactor(gameplay): keep host transition payloads in cartridge

fupogfakta/payloads.py

@@ -123,6 +123,17 @@ def build_scoreboard_phase_event(session: GameSession, leaderboard: list[dict] |
     }
 
 
+def build_reveal_scoreboard_response(session: GameSession, leaderboard: list[dict]) -> dict:
+    return {
+        "session": {
+            "code": session.code,
+            "status": session.status,
+            "current_round": session.current_round,
+        },
+        "leaderboard": leaderboard,
+    }
+
+
 def build_finish_game_phase_event(session: GameSession) -> dict:
     leaderboard = build_leaderboard(session)
     winner = leaderboard[0] if leaderboard else None