fix: remove non-functional panel toggle keyboard shortcuts

Removes Ctrl+B and Ctrl+I keyboard shortcuts that were causing panels
to disappear completely instead of collapsing properly. Also updates
all panel tooltips to no longer reference the removed shortcuts.

Changes:
- Removed Ctrl+B (left panel) and Ctrl+I (right panel) shortcut handlers
- Updated left panel tooltips: removed "(Ctrl+B)" references
- Updated right panel tooltips: removed "(Ctrl+I)" references
- Tooltips now simply show "Collapse Panel" / "Expand Panel"
- Escape key handler preserved for closing property panels

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

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

src/App.tsx

@@ -83,19 +83,9 @@ function AppContent() {
     onSelectAll: handleSelectAll,
   });
 
-  // Panel toggle keyboard shortcuts
+  // Escape key to close property panels
   useEffect(() => {
     const handleKeyDown = (e: KeyboardEvent) => {
-      // Ctrl+B: Toggle left panel
-      if (e.ctrlKey && e.key === 'b') {
-        e.preventDefault();
-        toggleLeftPanel();
-      }
-      // Ctrl+I: Toggle right panel
-      if (e.ctrlKey && e.key === 'i') {
-        e.preventDefault();
-        toggleRightPanel();
-      }
       // Escape: Close property panels
       if (e.key === 'Escape') {
         if (selectedNode || selectedEdge) {
@@ -108,7 +98,7 @@ function AppContent() {
 
     window.addEventListener('keydown', handleKeyDown);
     return () => window.removeEventListener('keydown', handleKeyDown);
-  }, [toggleLeftPanel, toggleRightPanel, selectedNode, selectedEdge]);
+  }, [selectedNode, selectedEdge]);
 
   return (
     <div className="flex flex-col h-screen bg-gray-100">

src/components/Panels/LeftPanel.tsx

@@ -71,7 +71,7 @@ const LeftPanel = ({ onDeselectAll, onAddNode }: LeftPanelProps) => {
   if (leftPanelCollapsed) {
     return (
       <div className="h-full bg-gray-50 border-r border-gray-200 flex flex-col items-center py-2 space-y-2" style={{ width: '40px' }}>
-        <Tooltip title="Expand Tools Panel (Ctrl+B)" placement="right">
+        <Tooltip title="Expand Tools Panel" placement="right">
           <IconButton size="small" onClick={expandLeftPanel}>
             <ChevronRightIcon fontSize="small" />
           </IconButton>
@@ -89,7 +89,7 @@ const LeftPanel = ({ onDeselectAll, onAddNode }: LeftPanelProps) => {
       {/* Header */}
       <div className="flex items-center justify-between px-3 py-2 border-b border-gray-200 bg-gray-50">
         <h2 className="text-sm font-semibold text-gray-700">Tools</h2>
-        <Tooltip title="Collapse Panel (Ctrl+B)">
+        <Tooltip title="Collapse Panel">
           <IconButton size="small" onClick={collapseLeftPanel}>
             <ChevronLeftIcon fontSize="small" />
           </IconButton>

src/components/Panels/RightPanel.tsx

@@ -47,7 +47,7 @@ const PanelHeader = ({ title, onClose, onCollapse }: PanelHeaderProps) => (
           </IconButton>
         </Tooltip>
       )}
-      <Tooltip title="Collapse Panel (Ctrl+I)">
+      <Tooltip title="Collapse Panel">
         <IconButton size="small" onClick={onCollapse}>
           <ChevronRightIcon fontSize="small" />
         </IconButton>
@@ -193,7 +193,7 @@ const RightPanel = ({ selectedNode, selectedEdge, onClose }: Props) => {
   if (rightPanelCollapsed) {
     return (
       <div className="h-full bg-gray-50 border-l border-gray-200 flex flex-col items-center py-2" style={{ width: '40px' }}>
-        <Tooltip title="Expand Properties Panel (Ctrl+I)" placement="left">
+        <Tooltip title="Expand Properties Panel" placement="left">
           <IconButton size="small" onClick={expandRightPanel}>
             <ChevronLeftIcon fontSize="small" />
           </IconButton>