修复模板库页无法上下滚动

- 模板库页面根节点补 platform-theme / platform-theme--light 与 h-full + overflow-y-auto：shell 只给 .launcher-main 下带 platform-theme 的直接子元素 height:100% + overflow:auto，缺这个类时整页没有滚动容器，模板一多就滚不动
- 补回归单测：页面根节点必须同时具备 platform-theme 与 overflow-y-auto

apps/ai-game-creator-shell/src/view/template-library/index.tsx

@@ -233,7 +233,7 @@ export default function TemplateLibraryView({
 
   return (
     <section
-      className="grid w-full content-start gap-4 px-6 pb-10 pt-5 max-[760px]:px-4"
+      className="platform-theme platform-theme--light grid h-full min-h-0 w-full content-start gap-4 overflow-x-hidden overflow-y-auto px-6 pb-10 pt-5 max-[760px]:px-4"
       aria-label="模板库"
     >
       <header className="flex flex-wrap items-center gap-3">

apps/ai-game-creator-shell/tests/templateLibraryView.test.tsx

@@ -135,6 +135,17 @@ describe('TemplateLibraryView', () => {
     ).toBeTruthy();
   });
 
+  it('renders the page as the launcher scroll container', () => {
+    // 回归点：`.launcher-main` 只给带 platform-theme 的直接子元素 height:100% + overflow:auto，
+    // 缺这个类时整页没有滚动容器（模板一多就滚不动）。
+    const { container } = render(
+      <TemplateLibraryView controller={controller()} onBack={() => {}} />,
+    );
+    const page = container.querySelector('section[aria-label="模板库"]');
+    expect(page?.className).toContain('platform-theme');
+    expect(page?.className).toContain('overflow-y-auto');
+  });
+
   it('offers 更新 instead of 下载 when the installed version is stale', () => {
     const stale = template({
       id: 'blank-web',