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.tsx

@@ -22,6 +22,7 @@ import { PlatformProfileRechargeModal } from '../../../packages/shared/src/compo
 import { PlatformProfileWalletLedgerModal } from '../../../packages/shared/src/components/PlatformProfileWalletLedgerModal';
 import type { ProfileDashboardSummary } from '../../../packages/shared/src/contracts/runtime';
 import {
+  hasAppHistoryBackEntry,
   pushAppHistoryPath,
   replaceAppHistoryPath,
 } from '../../routing/activeAppPageRoutes';
@@ -457,6 +458,33 @@ export function PlatformEntryFlowShellImpl({
     [setSelectionStage],
   );
 
+  /**
+   * 详情页可能从广场或「我的游戏」进入，返回优先走浏览器原生返回，这样能回到
+   * 用户真正的来源页；直接打开详情链接等没有可回退的应用内历史时再兜底回广场。
+   */
+  const backFromGameDetail = useCallback(() => {
+    if (hasAppHistoryBackEntry()) {
+      window.history.back();
+      return;
+    }
+    replaceAppHistoryPath('/games');
+    setSelectionStage('games', { path: '/games' });
+  }, [setSelectionStage]);
+
+  /** 游玩页同理，兜底是它自己的详情页，避免详情↔游玩互相塞历史条目。 */
+  const backFromGamePlay = useCallback(() => {
+    if (hasAppHistoryBackEntry()) {
+      window.history.back();
+      return;
+    }
+    const currentGameId = new URLSearchParams(window.location.search).get('id');
+    const path = currentGameId
+      ? `/games/detail?id=${encodeURIComponent(currentGameId)}`
+      : '/games';
+    replaceAppHistoryPath(path);
+    setSelectionStage(currentGameId ? 'game-detail' : 'games', { path });
+  }, [setSelectionStage]);
+
   const openEditorProject = useCallback(
     (projectId: string, options?: { guide?: boolean; tool?: string }) => {
       if (!isDesktopLayout) {
@@ -786,16 +814,11 @@ export function PlatformEntryFlowShellImpl({
                     ) : selectionStage === 'game-detail' ? (
                       <GameDetailPage
                         gameId={gameId}
-                        onBack={openGames}
+                        onBack={backFromGameDetail}
                         onPlay={openGamePlay}
                       />
                     ) : (
-                      <GamePlayPage
-                        gameId={gameId}
-                        onBack={() =>
-                          gameId ? openGameDetail(gameId) : openGames()
-                        }
-                      />
+                      <GamePlayPage gameId={gameId} onBack={backFromGamePlay} />
                     )}
                   </Suspense>
                 ) : (