docs(web): record V21 staging E2E validation

docs/V21-UI-ACCEPTANCE-CHECKLIST.md

@@ -173,3 +173,15 @@ V21 结构：三张套餐 feature 卡片，免费版/专业版/企业版，推
 - 已回滚危险 artifact build workflow：b01ae28 Revert "fix(deploy): build staging web artifact"。
 - 已给 deploy-staging.sh 增加硬保护：默认禁止 REBUILD_BACKEND=1 或 BUILD_WEB=1 在业务/staging deploy 路径上构建镜像；只有显式 ALLOW_STAGING_BUILDS=true 才允许在专用构建机执行。
 - 后续正式方案：CI/构建服务器产出 dist/image，业务服务器只接收产物并重启服务。
+
+
+## 2026-06-25 Staging Formal Validation
+
+- Git commit pushed: `f9a934d test(web): stabilize core E2E against V21 UI`.
+- Staging release path: `runtime-builder` built the Web image; the business server only loaded the image and restarted containers.
+- Staging Web image: `xiaoxia-saas-web:staging-f9a934d916cc4e1f1addad472bf90cb5eecffc0c`.
+- Staging health: `/login` returned 200; API `/health` returned healthy.
+- Local validation: `npm --prefix apps/web run type-check` passed; `npm --prefix apps/web run build` passed.
+- Staging Playwright: `auth/subscription/workspace/core-upload/core-titles/core-generation` passed, 6/6.
+- Core E2E update: setup uses `E2E_API_BASE` for direct API calls; browser `/api/v1` calls are routed through Playwright; assertions now match V21 asset/title/generation/result UI.
+- Staging migration note: lightweight Alembic migration added the `project_titles` table; no build ran on the business server.