修复图片画布生成尺寸与重复落图

同步图片生成与改造占位框到所选目标尺寸。

修复角色、图标和UI正常生成时中间原图重复进入画布的问题。

补充前后端回归测试并更新架构与项目记忆文档。

src/components/image-editor/ImageCanvasGenerationDialogModel.test.ts

@@ -538,6 +538,10 @@ describe('ImageCanvasGenerationDialogModel', () => {
       placeholder: {
         x: 472,
         y: 140,
+        width: 1024,
+        height: 768,
+        originalWidth: 1024,
+        originalHeight: 768,
       },
     });
 
@@ -614,9 +618,58 @@ describe('ImageCanvasGenerationDialogModel', () => {
       imageModel: 'gpt-image-2',
       aspectRatio: '2:3',
       imageSize: '2K',
+      placeholder: {
+        x: 472,
+        y: 140,
+        width: 1365,
+        height: 2048,
+        originalWidth: 1365,
+        originalHeight: 2048,
+      },
     });
   });
 
+  it.each([
+    ['character', 'character'],
+    ['icon', 'icon-spritesheet'],
+    ['ui-design', 'ui-design'],
+  ] as const)(
+    'restores %s remodel placeholders to the selected 2K dimensions',
+    (mode, assetKind) => {
+      expect(
+        createSameSourceGenerationDialogDraft({
+          sourceLayer: createLayer({ assetKind }),
+          canvasSize: { width: 960, height: 720 },
+          viewport: { x: 0, y: 0, scale: 1 },
+          sourceDialog: {
+            id: `generation-dialog-${mode}`,
+            mode,
+            prompt: '来源生成器',
+            status: 'idle',
+            generatedLayerId: 'layer-source',
+            imageModel: IMAGE_MODEL_GPT_IMAGE_2,
+            aspectRatio: '2:3',
+            imageSize: '2K',
+          },
+          mode: 'redraw',
+        }),
+      ).toMatchObject({
+        mode,
+        imageModel: IMAGE_MODEL_GPT_IMAGE_2,
+        aspectRatio: '2:3',
+        imageSize: '2K',
+        placeholder: {
+          x: 472,
+          y: 140,
+          width: 1365,
+          height: 2048,
+          originalWidth: 1365,
+          originalHeight: 2048,
+        },
+      });
+    },
+  );
+
   it('restores a plain generated layer from its own metadata', () => {
     const canvasSize = { width: 960, height: 720 };
     const viewport = { x: 0, y: 0, scale: 1 };