发布入口接入灰度开关

- 后端：GET /api/runtime/frontend-config 新增 gameDistributionPublishEnabled，复用 `game-distribution:publish` 判据（未配置或 enabled=false 时对已登录作者默认开放，显式收紧后只放行白名单/灰度命中用户，匿名恒为 false），前端入口与写入口共用同一事实源。
- 后端用例：新增 frontend_runtime_config_game_distribution_publish_is_scoped_to_authenticated_gate，覆盖默认开放、enabled=true 无白名单、白名单命中、deny 名单、enabled=false 回退与 rolloutPercent=100。
- 网页：平台壳按灰度隐藏「发布游戏 / 发布新版本」入口；/games/publish 直接访问时渲染「发布功能正在灰度中」并提供重新检查；读取失败按放行处理，由后端写入口把关并返回可读文案。
- AGC：新增 readGamePublishAvailability（同一运行时配置字段），只有命中才把发布回调交给 DirectProject 聊天头；字段缺失或读取失败按不开放处理。
- 文档：玩法链路、后端数据契约与实施计划记录灰度口径、入口行为与验证命令。

src/components/platform-entry/PlatformEntryActiveFlowShell.test.tsx

@@ -58,6 +58,15 @@ const gameDistributionMock = vi.hoisted(() => ({
 
 vi.mock('../../services/gameDistributionClient', () => gameDistributionMock);
 
+const frontendRuntimeConfigMock = vi.hoisted(() => ({
+  loadFrontendRuntimeConfig: vi.fn(),
+}));
+
+vi.mock('../../services/frontendRuntimeConfigService', () => ({
+  loadFrontendRuntimeConfig: (...args: unknown[]) =>
+    frontendRuntimeConfigMock.loadFrontendRuntimeConfig(...args),
+}));
+
 vi.mock('../auth/AuthUiContext', () => ({
   useAuthUi: () => authUiMock.value,
 }));
@@ -206,6 +215,12 @@ describe('PlatformEntryActiveFlowShell', () => {
     for (const mock of Object.values(gameDistributionMock)) {
       mock.mockReset();
     }
+    frontendRuntimeConfigMock.loadFrontendRuntimeConfig.mockReset();
+    frontendRuntimeConfigMock.loadFrontendRuntimeConfig.mockResolvedValue({
+      imageEditorAgentSidebarEnabled: false,
+      agcTemplateLibraryEnabled: false,
+      gameDistributionPublishEnabled: true,
+    });
     authUiMock.value.openLoginModal.mockReset();
     responsiveMock.isDesktopLayout = true;
   });
@@ -850,3 +865,47 @@ describe('PlatformEntryActiveFlowShell', () => {
     });
   });
 });
+
+describe('游戏发布灰度入口', () => {
+  function loginAsAuthor() {
+    authUiMock.value.user = {
+      id: 'user-1',
+      publicUserCode: '100001',
+      displayName: '测试作者',
+      avatarUrl: null,
+      phoneNumberMasked: null,
+      loginMethod: 'password',
+      bindingStatus: 'active',
+      wechatBound: false,
+    };
+    authUiMock.value.canAccessProtectedData = true;
+  }
+
+  it('灰度未命中时广场不展示发布入口', async () => {
+    loginAsAuthor();
+    frontendRuntimeConfigMock.loadFrontendRuntimeConfig.mockResolvedValue({
+      imageEditorAgentSidebarEnabled: false,
+      agcTemplateLibraryEnabled: false,
+      gameDistributionPublishEnabled: false,
+    });
+    gameDistributionMock.listGames.mockResolvedValue([]);
+
+    render(<StatefulPlatformEntryFlowShell initialStage="games" />);
+
+    expect(await screen.findByText('游戏广场')).toBeTruthy();
+    await waitFor(() =>
+      expect(screen.queryByRole('button', { name: '发布游戏' })).toBeNull(),
+    );
+  });
+
+  it('灰度命中时广场展示发布入口', async () => {
+    loginAsAuthor();
+    gameDistributionMock.listGames.mockResolvedValue([]);
+
+    render(<StatefulPlatformEntryFlowShell initialStage="games" />);
+
+    expect(
+      await screen.findByRole('button', { name: '发布游戏' }),
+    ).not.toBeNull();
+  });
+});