显示图标规范输入字符计数

在一键优化与撤销操作行右侧实时显示 Unicode 字符数和 200 字符上限。

补充计数更新、emoji 截断和右对齐布局测试，并同步编辑器方案文档。

src/components/image-editor/ImageCanvasSpecGenerationPanelView.test.tsx

@@ -355,6 +355,15 @@ describe('ImageCanvasSpecGenerationPanelView', () => {
       '玩法设定',
     ) as HTMLTextAreaElement;
     const artStyle = screen.getByLabelText('美术风格') as HTMLTextAreaElement;
+    expect(screen.getByLabelText('玩法设定字符计数').textContent).toBe(
+      '5/200',
+    );
+    expect(screen.getByLabelText('美术风格字符计数').textContent).toBe(
+      '4/200',
+    );
+    expect(screen.getByLabelText('玩法设定字符计数').className).toContain(
+      'ml-auto',
+    );
     expect(playSetting.hasAttribute('maxlength')).toBe(false);
     expect(artStyle.hasAttribute('maxlength')).toBe(false);
 
@@ -362,6 +371,9 @@ describe('ImageCanvasSpecGenerationPanelView', () => {
     expect(Array.from(playSetting.value)).toHaveLength(200);
     fireEvent.change(playSetting, { target: { value: '🎮'.repeat(201) } });
     expect(Array.from(playSetting.value)).toHaveLength(200);
+    expect(screen.getByLabelText('玩法设定字符计数').textContent).toBe(
+      '200/200',
+    );
     fireEvent.click(screen.getByRole('button', { name: '提交生成规范' }));
     expect(onSubmit).toHaveBeenCalledTimes(1);