fix(App): close context menu on right-click event

This change ensures that the repository tab context menu is closed
when the user right-clicks anywhere in the window. This improves
the user experience by preventing the context menu from remaining
open unintentionally.

- Added functionality to close the context menu on right-click.
- Updated event handling for context menu to use capture phase.

src/App.svelte

@@ -2801,6 +2801,7 @@
 
   function handleWindowContextMenu(event: MouseEvent) {
     event.preventDefault();
+    if (repoTabContextMenu) closeRepoTabContextMenu();
   }
 
   function handleWindowClick() {
@@ -2812,7 +2813,7 @@
   <title>GitLite</title>
 </svelte:head>
 
-<svelte:window on:click={handleWindowClick} on:keydown={handleWindowKeydown} on:contextmenu={handleWindowContextMenu} />
+<svelte:window on:click={handleWindowClick} on:keydown={handleWindowKeydown} on:contextmenu|capture={handleWindowContextMenu} />
 
 <main class="shell">
   <TitleBar