优化实例列表，限制宽度防止出现水平滚动条

[OrzMiku]

fix: #5240

[Copilot]

Pull request overview

This PR addresses issue #5240 by preventing horizontal scrollbars in the game instance list. The change sets the preferred width to 0 for the center HBox container in the GameListCell, which allows the JavaFX layout engine to properly constrain the content width.

Changes:

• Added center.setPrefWidth(0) to the center HBox in GameListCell to prevent horizontal overflow

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