feat(*): 画布创作 - 支持文本多模态生成并优化媒体节点、连接线与视频预览

Fixes #59

web/src/pages/canvas/project.tsx

@@ -202,7 +202,7 @@ function InfiniteCanvasPage() {
     const [hoveredNodeId, setHoveredNodeId] = useState<string | null>(null);
     const [contextMenu, setContextMenu] = useState<ContextMenuState | null>(null);
     const [isMiniMapOpen, setIsMiniMapOpen] = useState(false);
-    const [backgroundMode, setBackgroundMode] = useState<CanvasBackgroundMode>("lines");
+    const [backgroundMode, setBackgroundMode] = useState<CanvasBackgroundMode>("dots");
     const [showImageInfo, setShowImageInfo] = useState(false);
     const [mediaPerformanceMode, setMediaPerformanceMode] = useState<CanvasMediaPerformanceMode>(readCanvasMediaPerformanceMode);
     const [projectLoaded, setProjectLoaded] = useState(false);