feat(canvas): 画布媒体工作流 - 支持批量连线、失败重试与模型能力增强

合并 PR #230。保留当前主线样式与组件结构，吸收批量连线、失败批次重试、媒体模型能力和相关后端增强，并修复集成检查发现的分辨率选择器启用条件与测试稳定性问题。

web/src/lib/canvas/canvas-node-copy.ts

@@ -37,6 +37,7 @@ export function isolateCopiedNodeMetadata(node: CanvasNodeData, idMap: ReadonlyM
     delete metadata.generationBatches;
     delete metadata.batchRootId;
     delete metadata.batchChildIds;
+    delete metadata.batchFailedCount;
     delete metadata.isBatchRoot;
     delete metadata.primaryImageId;
     delete metadata.imageBatchExpanded;