收口元数据角标图标按钮

PlatformIconButton 增加 spanButton 形态，支持嵌套动作面合法复用图标按钮 chrome。

编辑器生成图元数据角标改为复用 PlatformIconButton，移除局部键盘处理。

补充测试覆盖 spanButton 键盘触发和元数据角标平台样式，并更新 TRACKING。

src/components/image-editor/ImageCanvasEditorView.tsx

@@ -2550,28 +2550,19 @@ export function ImageCanvasEditorView() {
                   >
                     <img src={layer.src} alt={`画布图片：${layer.title}`} />
                     {isGeneratedLayer(layer) ? (
-                      <span
+                      <PlatformIconButton
+                        asChild="spanButton"
+                        variant="darkMini"
                         className="image-canvas-editor__metadata-corner"
-                        role="button"
-                        tabIndex={0}
-                        aria-label={`查看${layer.title}元数据`}
+                        label={`查看${layer.title}元数据`}
+                        icon={<Braces className="h-3 w-3" />}
                         onClick={(event) => {
                           event.stopPropagation();
                           setMetadataLayer(layer);
                           selectSingleLayer(layer.id);
                         }}
                         onPointerDown={(event) => event.stopPropagation()}
-                        onKeyDown={(event) => {
-                          if (event.key === 'Enter' || event.key === ' ') {
-                            event.preventDefault();
-                            event.stopPropagation();
-                            setMetadataLayer(layer);
-                            selectSingleLayer(layer.id);
-                          }
-                        }}
-                      >
-                        <Braces className="h-3 w-3" />
-                      </span>
+                      />
                     ) : null}
                     {isHovered ? (
                       <span className="image-canvas-editor__size-badge">