feat(status-panel): add loading overlay for ongoing operations

This update introduces a loading overlay in the StatusPanel component
to indicate ongoing operations. The overlay displays a spinner and
the current operation status, enhancing user experience during
long-running tasks.

- Added a loading overlay with a spinner for busy states
- Included operation status text to inform users of current actions
- Improved visual feedback for ongoing processes in the UI

src/App.svelte

@@ -3734,6 +3734,7 @@
             {unstagedCount}
             {hasRepository}
             {isBusy}
+            {operation}
             {status}
             selectedFilePath={selectedExplorerPath}
             onSelectFile={selectFileFromStatus}