feat(keyboard): add Cmd+./Ctrl+. shortcut to toggle both sidebars

Reassign Cmd+. (Mac) and Ctrl+. (Win/Linux) from toggling the left
sidebar to toggling both sidebars at once. If either is open, both
close; if both are closed, both open. Left sidebar toggle on non-Mac
now uses Ctrl+B to match the Mac Cmd+B binding.

packages/app/src/stores/panel-store.ts

@@ -78,6 +78,7 @@ interface PanelState {
   closeToAgent: () => void;
   toggleAgentList: () => void;
   toggleFileExplorer: () => void;
+  toggleBothSidebars: () => void;
 
   // File explorer settings actions
   setExplorerTab: (tab: ExplorerTab) => void;
@@ -216,6 +217,24 @@ export const usePanelStore = create<PanelState>()(
           return nextState;
         }),
 
+      toggleBothSidebars: () =>
+        set((state) => {
+          // If either sidebar is open, close both. Otherwise, open both.
+          const anyOpen = state.desktop.agentListOpen || state.desktop.fileExplorerOpen;
+          if (anyOpen) {
+            return {
+              mobileView: "agent" as MobilePanelView,
+              desktop: { agentListOpen: false, fileExplorerOpen: false },
+            };
+          }
+          const resolvedTab = resolveExplorerTabFromActiveCheckout(state);
+          return {
+            mobileView: "agent" as MobilePanelView,
+            desktop: { agentListOpen: true, fileExplorerOpen: true },
+            ...(resolvedTab ? { explorerTab: resolvedTab } : {}),
+          };
+        }),
+
       setExplorerTab: (tab) => set({ explorerTab: tab }),
       setExplorerTabForCheckout: ({ serverId, cwd, isGit, tab }) =>
         set((state) => {