新增游戏买断制泥点付费真实本地栈 E2E 检查脚本

- 新增 scripts/check-game-distribution-purchase-e2e.mjs：覆盖付费游戏发布与审核、未购买用户无可播放入口且直连 404、购买扣泥点与幂等重放、播放会话可玩与重复进入不扣费、免费游戏回归、余额不足失败无副作用
- 脚本端口只读 .app/dev-stack.json 的实际地址，E2E_START_STACK=1 时自行拉起并收束本地 dev 栈
- 追加播放会话网关取证：伪造令牌 404、带平台 refresh Cookie 直连 403、经 dev 代理按前缀清空 Cookie 后仍可播放
- package.json 增加 check:game-distribution-purchase-e2e 别名

package.json

@@ -89,6 +89,7 @@
     "check:game-distribution-package-limits-e2e": "node scripts/check-game-distribution-package-limits-e2e.mjs",
     "check:game-distribution-validation-restart-e2e": "node scripts/check-game-distribution-validation-restart-e2e.mjs",
     "check:game-distribution-ops-rollback-e2e": "node scripts/check-game-distribution-ops-rollback-e2e.mjs",
+    "check:game-distribution-purchase-e2e": "node scripts/check-game-distribution-purchase-e2e.mjs",
     "check:production-ops": "node scripts/check-production-ops-guardrails.mjs",
     "check:preview-deployer": "node scripts/check-preview-deployer.mjs",
     "check:maintenance-page": "node scripts/check-maintenance-page.mjs",