fix(canvas): adjust overlay controls and restore add-to-chat action

components/canvas/CanvasWorkspace.tsx

@@ -1193,7 +1193,7 @@ export function CanvasWorkspace({ occlusionRight = 0 }: CanvasWorkspaceProps) {
 
       {/* 缩放控制器 */}
       {selectedImageNodes.length > 0 && (
-        <div className="absolute bottom-4 left-4 z-30" data-canvas-overlay>
+        <div className="absolute bottom-16 left-4 z-30" data-canvas-overlay>
           <Button
             variant="secondary"
             size="sm"

components/canvas/nodes/ImageNode.tsx

@@ -2067,11 +2067,19 @@ export function ImageNode({ node, isSelected }: ImageNodeProps) {
             onPointerDown={(e) => e.stopPropagation()}
             onClick={(e) => e.stopPropagation()}
           >
-            <div className="mr-1 inline-flex h-10 shrink-0 items-center gap-1.5 whitespace-nowrap rounded-xl bg-slate-900 px-3 text-[13px] font-semibold text-white dark:bg-slate-100 dark:text-slate-900">
-              <Sparkles className="h-4 w-4" />
-              <span className="whitespace-nowrap">快捷编辑</span>
-              <span className="whitespace-nowrap text-white/55 dark:text-slate-500">Tab</span>
-            </div>
+            <Button
+              variant="ghost"
+              disabled={isProcessing || isAddingToChat}
+              className="mr-1 inline-flex h-10 shrink-0 items-center gap-1.5 whitespace-nowrap rounded-xl bg-slate-900 px-3 text-[13px] font-semibold text-white hover:bg-slate-800 hover:text-white dark:bg-slate-100 dark:text-slate-900 dark:hover:bg-slate-200"
+              onClick={handleAddToChat}
+            >
+              {isAddingToChat ? (
+                <Loader2 className="h-4 w-4 animate-spin" />
+              ) : (
+                <MessageSquarePlus className="h-4 w-4" />
+              )}
+              <span className="whitespace-nowrap">添加对话</span>
+            </Button>
 
             <div className="mx-1 h-6 w-px bg-slate-200 dark:bg-slate-700" />