明确序列帧去背景处理模式

去背景弹窗要求用户显式选择纯色键控或通用智能分割。

纯色模式支持颜色输入和吸管取色，并以本地算法处理任意键色。

通用模式逐帧使用 BgFilter complex 分割，禁止携带键色。

入队与 durable worker 统一校验模式参数并持久化权威处理元数据。

补充双色键控、模式冲突、双路径路由和前端交互回归。

同步更新 Spine 技术方案与团队决策记录。

src/components/image-editor/useImageCanvasGenerationWorkflow.ts

@@ -19,6 +19,7 @@ import { uploadEditorMediaAssetFile } from '../../services/image-editor/editorMe
 import {
   createEditorProjectResource,
   type EditorAssetSnapshot,
+  type EditorCharacterAnimationBackgroundRemovalMode,
   type EditorPixelArtSnapInput,
   type EditorPixelArtSnapResult,
   type EditorProjectLayerSnapshot,
@@ -3676,7 +3677,13 @@ export function useImageCanvasGenerationWorkflow({
   );
 
   const removeSelectedCharacterAnimationBackground = useCallback(
-    async (sourceLayer: CanvasLayer) => {
+    async (
+      sourceLayer: CanvasLayer,
+      options: {
+        mode: EditorCharacterAnimationBackgroundRemovalMode;
+        screenColor?: string;
+      },
+    ) => {
       if (
         !canRemoveCharacterAnimationBackground(sourceLayer) ||
         !canSplitCharacterAnimationFrames(sourceLayer) ||
@@ -3716,6 +3723,10 @@ export function useImageCanvasGenerationWorkflow({
           projectId,
           sourceLayerId: sourceLayer.id,
           sourceResourceId: sourceLayer.resourceId,
+          mode: options.mode,
+          ...(options.mode === 'solid-color' && options.screenColor
+            ? { screenColor: options.screenColor }
+            : {}),
           assetFolderId,
           assetLabel,
           ...(backgroundRemovalPlacement?.placeholder