详情页返回按来源回到上一页并改用浏览器原生返回

- GameDetailPage 左上角「返回游戏广场」简化为「返回」，不再写死跳广场
- 详情/游玩页返回优先 window.history.back()，由 popstate 还原真实来源页（我的游戏/广场）
- activeAppPageRoutes 给应用历史条目补深度标记并新增 hasAppHistoryBackEntry()
- 深链直开等无可回退条目时用 replaceAppHistoryPath 兜底回广场或详情
- 新增 activeAppPageRoutes 深度语义用例与 PlatformEntryActiveFlowShell「游戏详情返回」两条用例
- 同步里程碑文档 2026-09-30 与 pitfalls 同日条目

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

@@ -12,6 +12,7 @@ import { type ReactElement, type ReactNode, useState } from 'react';
 import { beforeEach, describe, expect, it, vi } from 'vitest';
 
 import type { AuthUser } from '../../../packages/shared/src/contracts/auth';
+import { pushAppHistoryPath } from '../../routing/activeAppPageRoutes';
 import {
   usePlatformWalletLifecycle,
   usePlatformWalletStore,
@@ -938,3 +939,76 @@ describe('游戏发布灰度入口', () => {
     ).not.toBeNull();
   });
 });
+
+describe('游戏详情返回', () => {
+  function mockDetailGame() {
+    gameDistributionMock.getGame.mockResolvedValue({
+      id: 'game-1',
+      title: '星轨防线',
+      summary: '守住轨道城',
+      description: '一款测试游戏。',
+      category: '动作',
+      tags: ['塔防'],
+      coverColor: '#d77a51',
+      icon: '✦',
+      author: { id: 'author-1', name: '测试作者' },
+      deviceSupport: { desktop: true, mobile: true, touch: true },
+      status: 'published',
+      currentVersion: {
+        id: 'version-1',
+        version: '1.0.0',
+        entryUrl: 'https://play.example.test/releases/version-1/index.html',
+        sha256: 'sha256',
+        publishedAt: '2026-09-18T00:00:00.000Z',
+        controls: ['键盘'],
+      },
+      playCount: 12,
+      createdAt: '2026-09-18T00:00:00.000Z',
+    });
+  }
+
+  async function clickDetailBack() {
+    fireEvent.click(await screen.findByRole('button', { name: '返回' }));
+  }
+
+  it('返回按钮不再写死广场文案与目标，改走浏览器原生返回', async () => {
+    mockDetailGame();
+    window.history.replaceState(null, '', '/games/mine');
+    pushAppHistoryPath('/games/detail?id=game-1');
+    const backSpy = vi
+      .spyOn(window.history, 'back')
+      .mockImplementation(() => {});
+    const setSelectionStage = vi.fn();
+
+    render(
+      <PlatformEntryFlowShellImpl
+        selectionStage="game-detail"
+        setSelectionStage={setSelectionStage}
+      />,
+    );
+    await clickDetailBack();
+
+    expect(backSpy).toHaveBeenCalledTimes(1);
+    expect(setSelectionStage).not.toHaveBeenCalled();
+    backSpy.mockRestore();
+  });
+
+  it('直接打开详情链接时返回兜底回游戏广场', async () => {
+    mockDetailGame();
+    window.history.replaceState(null, '', '/games/detail?id=game-1');
+    const setSelectionStage = vi.fn();
+
+    render(
+      <PlatformEntryFlowShellImpl
+        selectionStage="game-detail"
+        setSelectionStage={setSelectionStage}
+      />,
+    );
+    await clickDetailBack();
+
+    expect(setSelectionStage).toHaveBeenCalledWith('games', {
+      path: '/games',
+    });
+    expect(window.location.pathname).toBe('/games');
+  });
+});