限制序列帧去背景仅用于视频转换

后端仅接受 character-animation.convert 结果执行序列帧去背景

前端工具栏与工作流同步收紧视频转换门禁

更新相关测试与Spine序列帧技术方案

src/components/image-editor/useImageCanvasGenerationWorkflow.ts

@@ -96,6 +96,7 @@ import {
   appendLimitedImageReferences,
   buildDeterministicGenerationInputs,
   calculateCharacterAnimationPrice,
+  canRemoveCharacterAnimationBackground,
   canSplitCharacterAnimationFrames,
   CANVAS_GENERATION_PARAMETER_FALLBACK_WARNING,
   CHARACTER_ANIMATION_DURATION_OPTIONS,
@@ -3677,6 +3678,7 @@ export function useImageCanvasGenerationWorkflow({
   const removeSelectedCharacterAnimationBackground = useCallback(
     async (sourceLayer: CanvasLayer) => {
       if (
+        !canRemoveCharacterAnimationBackground(sourceLayer) ||
         !canSplitCharacterAnimationFrames(sourceLayer) ||
         !projectId ||
         removingBackgroundCharacterAnimationLayerIdsRef.current.has(