fix: 关系图谱适配画布改用独立 Scan 图标

适配画布与全屏图标视觉冲突，改为 ScanOutlined，与全屏 FullscreenOutlined 明显区分。

ai-electron/frontend/src/ai/components/graph/GraphAnalysisViewer.vue

@@ -190,7 +190,7 @@
             </Tooltip>
             <Tooltip title="适配画布">
               <Button type="text" class="canvas-toolbar__button" @click="fitView">
-                <CompressOutlined />
+                <ScanOutlined />
               </Button>
             </Tooltip>
             <span class="canvas-toolbar__divider"></span>
@@ -296,9 +296,9 @@
   import {
     AimOutlined,
     ApartmentOutlined,
-    CompressOutlined,
     FilterOutlined,
     FullscreenOutlined,
+    ScanOutlined,
     SearchOutlined,
     ShareAltOutlined,
   } from '@ant-design/icons-vue';