feat: centralize keyboard shortcuts through shortcut manager

All keyboard shortcut labels in the MenuBar now come from the
centralized keyboard shortcut manager via the new useShortcutLabels
hook, eliminating hardcoded duplicates.

Changes:
- Add useShortcutLabels hook for retrieving formatted shortcut labels
- Update MenuBar to use dynamic shortcut labels from manager
- Platform-aware display (Cmd on Mac, Ctrl elsewhere)
- Shortcuts automatically update if changed in manager
- Fix MUI icon fontSize prop issue in LeftPanel

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/components/Menu/MenuBar.tsx

@@ -6,6 +6,7 @@ import DocumentManager from '../Workspace/DocumentManager';
 import NodeTypeConfigModal from '../Config/NodeTypeConfig';
 import EdgeTypeConfigModal from '../Config/EdgeTypeConfig';
 import { useConfirm } from '../../hooks/useConfirm';
+import { useShortcutLabels } from '../../hooks/useShortcutLabels';
 
 /**
  * MenuBar Component
@@ -30,6 +31,7 @@ const MenuBar: React.FC<MenuBarProps> = ({ onOpenHelp, onFitView, onSelectAll })
   const [showEdgeConfig, setShowEdgeConfig] = useState(false);
   const menuRef = useRef<HTMLDivElement>(null);
   const { confirm, ConfirmDialogComponent } = useConfirm();
+  const { getShortcutLabel } = useShortcutLabels();
 
   const {
     createDocument,
@@ -168,7 +170,9 @@ const MenuBar: React.FC<MenuBarProps> = ({ onOpenHelp, onFitView, onSelectAll })
                   className="w-full text-left px-4 py-2 text-sm text-gray-700 hover:bg-gray-100 flex items-center justify-between"
                 >
                   <span>New Document</span>
-                  <span className="text-xs text-gray-400">Ctrl+N</span>
+                  {getShortcutLabel('new-document') && (
+                    <span className="text-xs text-gray-400">{getShortcutLabel('new-document')}</span>
+                  )}
                 </button>
                 <button
                   onClick={handleNewDocumentFromTemplate}
@@ -182,7 +186,9 @@ const MenuBar: React.FC<MenuBarProps> = ({ onOpenHelp, onFitView, onSelectAll })
                   className="w-full text-left px-4 py-2 text-sm text-gray-700 hover:bg-gray-100 flex items-center justify-between"
                 >
                   <span>Document Manager</span>
-                  <span className="text-xs text-gray-400">Ctrl+O</span>
+                  {getShortcutLabel('open-document-manager') && (
+                    <span className="text-xs text-gray-400">{getShortcutLabel('open-document-manager')}</span>
+                  )}
                 </button>
 
                 <hr className="my-1 border-gray-200" />
@@ -198,7 +204,9 @@ const MenuBar: React.FC<MenuBarProps> = ({ onOpenHelp, onFitView, onSelectAll })
                   className="w-full text-left px-4 py-2 text-sm text-gray-700 hover:bg-gray-100 flex items-center justify-between"
                 >
                   <span>Export Document</span>
-                  <span className="text-xs text-gray-400">Ctrl+S</span>
+                  {getShortcutLabel('save-document') && (
+                    <span className="text-xs text-gray-400">{getShortcutLabel('save-document')}</span>
+                  )}
                 </button>
                 <button
                   onClick={handleExportAll}
@@ -290,7 +298,9 @@ const MenuBar: React.FC<MenuBarProps> = ({ onOpenHelp, onFitView, onSelectAll })
                   className="w-full text-left px-4 py-2 text-sm text-gray-700 hover:bg-gray-100 flex items-center justify-between"
                 >
                   <span>Fit View to Content</span>
-                  <span className="text-xs text-gray-400">F</span>
+                  {getShortcutLabel('fit-view') && (
+                    <span className="text-xs text-gray-400">{getShortcutLabel('fit-view')}</span>
+                  )}
                 </button>
                 <button
                   onClick={() => {
@@ -300,7 +310,9 @@ const MenuBar: React.FC<MenuBarProps> = ({ onOpenHelp, onFitView, onSelectAll })
                   className="w-full text-left px-4 py-2 text-sm text-gray-700 hover:bg-gray-100 flex items-center justify-between"
                 >
                   <span>Select All</span>
-                  <span className="text-xs text-gray-400">Ctrl+A</span>
+                  {getShortcutLabel('select-all') && (
+                    <span className="text-xs text-gray-400">{getShortcutLabel('select-all')}</span>
+                  )}
                 </button>
               </div>
             )}
@@ -330,7 +342,9 @@ const MenuBar: React.FC<MenuBarProps> = ({ onOpenHelp, onFitView, onSelectAll })
                   className="w-full text-left px-4 py-2 text-sm text-gray-700 hover:bg-gray-100 flex items-center justify-between"
                 >
                   <span>Keyboard Shortcuts</span>
-                  <span className="text-xs text-gray-400">?</span>
+                  {getShortcutLabel('show-help') && (
+                    <span className="text-xs text-gray-400">{getShortcutLabel('show-help')}</span>
+                  )}
                 </button>
               </div>
             )}

src/components/Panels/LeftPanel.tsx

@@ -125,8 +125,8 @@ const LeftPanel = ({ onDeselectAll, onAddNode }: LeftPanelProps) => {
                     title={nodeType.description}
                   >
                     {IconComponent ? (
-                      <div className="w-5 h-5 flex items-center justify-center" style={{ color: textColor }}>
+                      <div className="w-5 h-5 flex items-center justify-center" style={{ color: textColor, fontSize: '1.25rem' }}>
-                        <IconComponent style={{ fontSize: '1.25rem' }} />
+                        <IconComponent />
                       </div>
                     ) : (
                       <div

src/hooks/useShortcutLabels.ts

@@ -0,0 +1,48 @@
+import { useCallback } from 'react';
+import { useKeyboardShortcuts } from './useKeyboardShortcuts';
+
+/**
+ * useShortcutLabels Hook
+ *
+ * Provides a convenient API for getting formatted keyboard shortcut labels
+ * from the centralized keyboard shortcut manager.
+ *
+ * This hook is useful for displaying shortcuts in:
+ * - Menu items
+ * - Tooltips
+ * - Context menus
+ * - Button labels
+ * - Any UI element that needs to show keyboard shortcuts
+ *
+ * Usage:
+ * ```tsx
+ * const { getShortcutLabel } = useShortcutLabels();
+ * const label = getShortcutLabel('new-document'); // Returns "Ctrl+N" or "Cmd+N" on Mac
+ * ```
+ */
+export function useShortcutLabels() {
+  const { shortcuts } = useKeyboardShortcuts();
+
+  /**
+   * Get the formatted label for a keyboard shortcut by its ID
+   *
+   * @param shortcutId - The unique identifier for the shortcut
+   * @returns Formatted shortcut string (e.g., "Ctrl+N") or null if shortcut doesn't exist or is disabled
+   */
+  const getShortcutLabel = useCallback(
+    (shortcutId: string): string | null => {
+      const allShortcuts = shortcuts.getAllShortcuts();
+      const shortcut = allShortcuts.find((s) => s.id === shortcutId);
+
+      // Return null if shortcut doesn't exist or is disabled
+      if (!shortcut || shortcut.enabled === false) {
+        return null;
+      }
+
+      return shortcuts.formatShortcut(shortcut);
+    },
+    [shortcuts]
+  );
+
+  return { getShortcutLabel };
+}