fix: 工具栏显示在图片外部上方

1. 修改画布容器为 overflow-visible
2. 工具栏定位到图片上方 (-top-12)
3. 提高 z-index 确保不被遮挡

Co-authored-by: Cursor <cursoragent@cursor.com>

components/canvas/CanvasWorkspace.tsx

@@ -217,7 +217,7 @@ export function CanvasWorkspace() {
     <div
       ref={containerRef}
       className={cn(
-        "relative w-full h-full overflow-hidden bg-background",
+        "relative w-full h-full overflow-visible bg-background",
         tool === 'pan' && "cursor-grab",
         isPanning && "cursor-grabbing"
       )}

components/canvas/nodes/ImageNode.tsx

@@ -392,10 +392,10 @@ export function ImageNode({ node, isSelected }: ImageNodeProps) {
           </div>
         )}
 
-        {/* 选中时显示的顶部工具栏 - 放在图片内部顶部，避免被裁剪 */}
+        {/* 选中时显示的顶部工具栏 - 显示在图片外部上方 */}
         {isSelected && data.src && !isProcessing && (
           <div 
-            className="absolute top-2 left-1/2 -translate-x-1/2 flex items-center gap-0.5 bg-white/95 backdrop-blur-sm border border-gray-200 rounded-full shadow-xl px-2 py-1.5 z-50"
+            className="absolute -top-12 left-1/2 -translate-x-1/2 flex items-center gap-0.5 bg-white border border-gray-200 rounded-full shadow-xl px-3 py-1.5 z-[100]"
             style={{ 
               pointerEvents: 'auto',
               minWidth: 'max-content',