Initial commit: clean project structure

- Backend: FastAPI + SQLAlchemy + Celery (Python 3.11+)
- Frontend: Vue 3 + TypeScript + Pinia + Tailwind
- Admin Frontend: separate Vue 3 app for management
- Docker Compose: 9 services orchestration
- Specs: design prototypes, memory system PRD, product roadmap

Cleanup performed:
- Removed temporary debug scripts from backend root
- Removed deprecated admin_app.py (embedded UI)
- Removed duplicate docs from admin-frontend
- Updated .gitignore for Vite cache and egg-info

backend/alembic/README.md

@@ -0,0 +1,20 @@
+# Alembic 使用说明
+
+1. 安装依赖（在后端虚拟环境内）
+```
+pip install alembic
+```
+
+2. 设置环境变量，确保 `DATABASE_URL` 指向目标数据库。
+
+3. 运行迁移：
+```
+alembic upgrade head
+```
+
+4. 生成新迁移（如有模型变更）：
+```
+alembic revision -m "message" --autogenerate
+```
+
+说明：`alembic/env.py` 会从 `app.core.config` 读取数据库 URL，并包含 admin/provider 模型。