s&box Razor UI: SpawnMenu with Mode Switching and PanelComponent

Implementing UI in s&box using Razor requires understanding the component model, SCSS styling, input handling, and integration with game state. Common challenges include:

1. Creating Razor panels that update from game state
2. Handling input focus for in-game menus
3. Implementing mode switching (spawn menu, context menu, etc.)
4. Styling with SCSS in s&box's UI framework