🎉 Initial commit: QQuiz - 智能刷题与题库管理平台

## 功能特性

✅ **核心功能**
- 多文件上传与智能去重（基于 content_hash）
- 异步文档解析（支持 TXT/PDF/DOCX/XLSX）
- AI 智能题目提取与评分（OpenAI/Anthropic/Qwen）
- 断点续做与进度管理
- 自动错题本收集

✅ **技术栈**
- Backend: FastAPI + SQLAlchemy 2.0 + PostgreSQL
- Frontend: React 18 + Vite + Tailwind CSS
- Deployment: Docker Compose

✅ **项目结构**
- 53 个文件
- 完整的前后端分离架构
- Docker/源码双模部署支持

🚀 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

backend/routers/admin.py

@@ -0,0 +1,63 @@
+"""
+Admin Router
+"""
+from fastapi import APIRouter, Depends, HTTPException
+from sqlalchemy.ext.asyncio import AsyncSession
+from sqlalchemy import select
+
+from database import get_db
+from models import User, SystemConfig
+from schemas import SystemConfigUpdate, SystemConfigResponse
+from services.auth_service import get_current_admin_user
+
+router = APIRouter()
+
+
+@router.get("/config", response_model=SystemConfigResponse)
+async def get_system_config(
+    current_admin: User = Depends(get_current_admin_user),
+    db: AsyncSession = Depends(get_db)
+):
+    """Get system configuration (admin only)"""
+
+    # Fetch all config values
+    result = await db.execute(select(SystemConfig))
+    configs = {config.key: config.value for config in result.scalars().all()}
+
+    return {
+        "allow_registration": configs.get("allow_registration", "true").lower() == "true",
+        "max_upload_size_mb": int(configs.get("max_upload_size_mb", "10")),
+        "max_daily_uploads": int(configs.get("max_daily_uploads", "20")),
+        "ai_provider": configs.get("ai_provider", "openai")
+    }
+
+
+@router.put("/config", response_model=SystemConfigResponse)
+async def update_system_config(
+    config_update: SystemConfigUpdate,
+    current_admin: User = Depends(get_current_admin_user),
+    db: AsyncSession = Depends(get_db)
+):
+    """Update system configuration (admin only)"""
+
+    update_data = config_update.dict(exclude_unset=True)
+
+    for key, value in update_data.items():
+        result = await db.execute(
+            select(SystemConfig).where(SystemConfig.key == key)
+        )
+        config = result.scalar_one_or_none()
+
+        if config:
+            config.value = str(value).lower() if isinstance(value, bool) else str(value)
+        else:
+            new_config = SystemConfig(
+                key=key,
+                value=str(value).lower() if isinstance(value, bool) else str(value)
+            )
+            db.add(new_config)
+
+    await db.commit()
+
+    # Return updated config
+    return await get_system_config(current_admin, db)