Function addSidebarButton

addSidebarButton(
    text: string,
    iconClass: Icon,
    onClick: () => void,
    href?: string,
): null | HTMLLIElement
Adds a button to the sidebar panel of the NationStates interface.

The sidebar is the vertical navigation panel on the left (inside div#panel). Buttons are added to the main menu list (ul.menu).
Parameters
- text: string
  The text label for the button.
- iconClass: Icon
  The CSS class for the button's icon (e.g., "globe", "radar").
- onClick: () => void
  A function to be called when the button is clicked.
- href: string = "#"
  The URL the button should link to. Defaults to "#" for action-only buttons.
Returns null | HTMLLIElement
The created list item element (HTMLLIElement) or null if a required container element is not found.
- Defined in gui/sideBarButton.ts:16