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

.gitignore

@@ -0,0 +1,40 @@
+# Python
+__pycache__/
+*.py[cod]
+*$py.class
+*.so
+.Python
+.venv/
+venv/
+ENV/
+
+# Node
+node_modules/
+dist/
+
+# IDE
+.idea/
+.vscode/
+*.swp
+*.swo
+
+# 环境变量
+.env
+
+# 测试
+.pytest_cache/
+.coverage
+htmlcov/
+
+# 其他
+*.log
+.DS_Store
+
+# Vite
+*.timestamp-*.mjs
+
+# Python packaging
+*.egg-info/
+
+# Alembic
+alembic/__pycache__/