完善文档与前端迁移，补充开源协议

web/README.md

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+# QQuiz Web
+
+This directory contains the new Next.js frontend scaffold for the QQuiz
+refactor.
+
+## Status
+
+- App Router skeleton: added
+- Auth/session proxy routes: added
+- Legacy Vite frontend replacement: in progress
+- shadcn/ui component foundation: added
+
+## Environment
+
+Copy `.env.example` and point `API_BASE_URL` at the FastAPI backend.