feat(short-drama-agent-front): 优化图片加载动效

tests/components/ui/AssetImage.test.ts

@@ -33,19 +33,15 @@ describe('资源图片展示与原图预览', () => {
         expect(wrapper.get<HTMLImageElement>('img').element.style.objectFit).toBe('contain')
     })
 
-    it('图片加载完成后按网格逐块显现，并在动画结束后移除覆盖层', async () => {
-        vi.useFakeTimers()
-        vi.stubGlobal('requestAnimationFrame', (callback: FrameRequestCallback) => {
-            callback(0)
-            return 1
-        })
-        wrapper = mount(AssetImage, { props: { src: '/storage/reveal.png', alt: '加载动效图片' } })
-        expect(wrapper.findAll('.reveal-image-cell')).toHaveLength(16)
+    it('图片加载前显示轻量骨架占位，加载完成后直接淡入图片并移除占位', async () => {
+        wrapper = mount(AssetImage, { props: { src: '/storage/reveal.png', alt: '加载中的图片' } })
+        expect(wrapper.get('.reveal-image').attributes('aria-busy')).toBe('true')
+        expect(wrapper.find('.reveal-image-placeholder').exists()).toBe(true)
+        expect(wrapper.find('.reveal-image-grid').exists()).toBe(false)
         await wrapper.get('img').trigger('load')
         expect(wrapper.get('.reveal-image').classes()).toContain('is-loaded')
-        vi.advanceTimersByTime(760)
-        await wrapper.vm.$nextTick()
-        expect(wrapper.find('.reveal-image-grid').exists()).toBe(false)
+        expect(wrapper.get('.reveal-image').attributes('aria-busy')).toBe('false')
+        expect(wrapper.find('.reveal-image-placeholder').exists()).toBe(false)
     })
 
     it('cover 仅裁切卡片，点击使用 Naive 原生预览展示同一完整资源，遮罩可关闭', async () => {