新增「原版与二创对比」页与路由登记（含 nginx×3 + Pingora allowlist）

- 新增路由 /games/compare（stage game-compare）：STAGE_ROUTE_ENTRIES + SelectionStage 类型 + 壳层 lazy 引入/导航回调/渲染分支 + 页面标题，四处同批登记
- 三份 nginx SPA allowlist（deploy/nginx/genarrative.conf、deploy/nginx/genarrative-dev-http.conf、deploy/container/nginx.conf）与 Pingora MAIN_SPA_PATHS 同步放行 /games/compare（保持既有排序）：check:nginx-spa-routes 18 SPA routes、check:pingora-route-parity 均绿
- 对比页左右两侧各自取数与降级：任一侧不可读（不存在/未公开/已软删除）或没有可玩版本时只降级那一侧，另一侧照常；显示标题、作者与代际；桌面左右并排、窄屏上下堆叠
- iframe 复用游玩页同一份嵌入：抽出 GamePlayFrame（sandbox=allow-scripts、allow=fullscreen、referrerPolicy=no-referrer、.game-player-frame），游玩页改为渲染它，不再存在第二套嵌入逻辑
- 入口：二创作品详情页在存在父作品时给出「与原版对比」；族谱节点仅在其父作品可见时给出同一入口
- 测试：对比页两侧渲染与 iframe 复用属性、单侧降级后另一侧照常；详情页入口（有/无父作品）；族谱节点入口（父可见才出现）；路由与标题登记；壳层「族谱节点→对比页」导航与对比 stage 渲染
- 顺手：按 eslint 自动修复两个文件的 import 排序

src/components/platform-entry/PlatformEntryActiveFlowShell.tsx

@@ -120,6 +120,11 @@ const GameLineagePage = lazy(async () => {
   return { default: module.GameLineagePage };
 });
 
+const GameComparePage = lazy(async () => {
+  const module = await import('../game-distribution/GameComparePage');
+  return { default: module.GameComparePage };
+});
+
 type ActiveRailButtonProps = {
   active: boolean;
   emphasized?: boolean;
@@ -565,6 +570,29 @@ export function PlatformEntryFlowShellImpl({
     setSelectionStage('games', { path: '/games' });
   }, [setSelectionStage]);
 
+  /** 打开「原版与二创对比」：左侧原版（父作品）、右侧二创（当前作品）。 */
+  const openGameCompare = useCallback(
+    (leftGameId: string, rightGameId: string) => {
+      const params = new URLSearchParams({
+        left: leftGameId,
+        right: rightGameId,
+      });
+      const path = `/games/compare?${params.toString()}`;
+      setSelectionStage('game-compare', { path });
+    },
+    [setSelectionStage],
+  );
+
+  /** 对比页同理：原生返回优先，兜底回广场。 */
+  const backFromGameCompare = useCallback(() => {
+    if (hasAppHistoryBackEntry()) {
+      window.history.back();
+      return;
+    }
+    replaceAppHistoryPath('/games');
+    setSelectionStage('games', { path: '/games' });
+  }, [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。
@@ -699,6 +727,7 @@ export function PlatformEntryFlowShellImpl({
   const isGamesStage =
     selectionStage === 'games' ||
     selectionStage === 'game-detail' ||
+    selectionStage === 'game-compare' ||
     selectionStage === 'game-play' ||
     selectionStage === 'game-mine' ||
     selectionStage === 'game-lineage' ||
@@ -713,6 +742,8 @@ export function PlatformEntryFlowShellImpl({
   );
   const gameId = gameSearchParams.get('id');
   const lineageHighlightGameId = gameSearchParams.get('from');
+  const compareLeftGameId = gameSearchParams.get('left');
+  const compareRightGameId = gameSearchParams.get('right');
   const creatorConnectionTab = gameSearchParams.get('tab');
   const publishGameId = gameSearchParams.get('game');
   const avatarUrl = authUi?.user?.avatarUrl?.trim() || null;
@@ -1005,6 +1036,7 @@ export function PlatformEntryFlowShellImpl({
                         onBack={backFromGameDetail}
                         onPlay={openGamePlay}
                         onOpenLineage={openGameLineage}
+                        onOpenCompare={openGameCompare}
                       />
                     ) : selectionStage === 'game-lineage' ? (
                       <GameLineagePage
@@ -1012,6 +1044,14 @@ export function PlatformEntryFlowShellImpl({
                         highlightGameId={lineageHighlightGameId}
                         onBack={backFromGameLineage}
                         onOpenDetail={openGameDetail}
+                        onOpenCompare={openGameCompare}
+                      />
+                    ) : selectionStage === 'game-compare' ? (
+                      <GameComparePage
+                        leftGameId={compareLeftGameId}
+                        rightGameId={compareRightGameId}
+                        onBack={backFromGameCompare}
+                        onOpenDetail={openGameDetail}
                       />
                     ) : (
                       <GamePlayPage gameId={gameId} onBack={backFromGamePlay} />