fix(canvas): 人物质感变体自动触发生成，修复缩略图不变 #91 (#92)

- use-canvas-media-tools.ts: createPortraitTextureNode 改为 generatePortraitTextureNode，
  节点创建后立即触发后端生成任务（与情绪/多视角/局部编辑保持一致）：
  使用 nodeReferenceImage 获取源图引用，buildPortraitTexturePrompt 构建提示词，
  runBackendCanvasGenerationTask 执行生成，完成后更新缩略图
- project.tsx: 同步重命名 createPortraitTextureNode → generatePortraitTextureNode
- canvas-drawing-excalidraw-editor.tsx: getDimensions 参数补充 number 类型注解
- canvas-drawing-editor-modal.tsx: Pick 类型补充 engine 字段

Co-authored-by: sikongyue <3155157671@qq.com>

web/src/pages/canvas/project.tsx

@@ -509,7 +509,7 @@ function InfiniteCanvasPage() {
         emotionNodeId,
         annotationNodeId,
         createImageReversePromptNodes,
-        createPortraitTextureNode,
+        generatePortraitTextureNode,
         cropImageNode,
         cropNodeId,
         extractVideoLastFrame,
@@ -1557,7 +1557,7 @@ function InfiniteCanvasPage() {
                     onAnnotate={(node) => setAnnotationNodeId(node.id)}
                     onMaskEdit={(node) => setMaskEditNodeId(node.id)}
                     onEmotion={(node) => { setDialogNodeId(null); setEmotionNodeId((current) => current === node.id ? null : node.id); }}
-                    onPortraitTexture={createPortraitTextureNode}
+                    onPortraitTexture={generatePortraitTextureNode}
                     onCrop={(node) => setCropNodeId(node.id)}
                     onSplit={(node) => setSplitNodeId(node.id)}
                     onUpscale={(node) => setUpscaleNodeId(node.id)}