feat(lobby): drop left honest-AI games from the finished list

A finished honest-AI (vs_ai) game the player left — by resigning or by
abandoning it to the 7-day inactivity timeout (end_reason 'resign'/'timeout')
— no longer appears in that player's own lobby finished list.

The new game.Service.ListForLobby filters ListForAccount for the lobby
endpoint only; the admin console and the account-merge count keep the full
set. The filter keys on the game's end reason, not on which seat left, so it
extends to any player should the robot ever resign.

backend/internal/server/handlers_game.go

@@ -421,14 +421,16 @@ func (s *Server) ensureUnderGameLimit(c *gin.Context, uid uuid.UUID) bool {
 	return true
 }
 
-// handleListGames returns the caller's active and finished games for the lobby.
+// handleListGames returns the caller's active and finished games for the lobby. It omits
+// the honest-AI games the caller left (resigned or abandoned to timeout); see
+// game.Service.ListForLobby.
 func (s *Server) handleListGames(c *gin.Context) {
 	uid, ok := userID(c)
 	if !ok {
 		abortBadRequest(c, "missing identity")
 		return
 	}
-	games, err := s.games.ListForAccount(c.Request.Context(), uid)
+	games, err := s.games.ListForLobby(c.Request.Context(), uid)
 	if err != nil {
 		s.abortErr(c, err)
 		return