Surface workspace changes from agent panes (#3682)

* feat(app): refine workspace pane actions

Prioritize Changes when available, keep Files useful before a selection, and reserve desktop diff clicks for selection so comments require the explicit affordance. Move the Changes shortcut to Shift+G to avoid consuming a likely copy variant.

* feat(app): improve access to workspace changes

packages/app/src/components/file-explorer-pane.tsx

@@ -1662,7 +1662,6 @@ function getErrorRecoveryPath(state: AgentFileExplorerState | undefined): string
 const styles = StyleSheet.create((theme) => ({
   container: {
     flex: 1,
-    backgroundColor: theme.colors.surfaceSidebar,
   },
   desktopSplit: {
     flex: 1,