重构: 迁移后端代码到 app 目录，前端移动到 WebUI，添加完整测试套件

主要变更:
- 后端代码从根目录迁移到 app/ 目录
- 前端代码从 frontend/ 重命名为 WebUI/
- 更新所有导入路径以适配新结构
- 提取公共 API 响应函数到 app/api/common.py
- 精简验证器服务代码
- 更新启动脚本和文档

测试:
- 新增完整测试套件 (tests/)
- 单元测试: 模型、仓库层
- 集成测试: 覆盖所有 22+ API 端点
- E2E 测试: 4个完整工作流场景
- 添加 pytest 配置和测试运行脚本

app/api/routes/proxies.py

@@ -0,0 +1,125 @@
+"""代理相关路由（含统计信息）"""
+from typing import Optional
+from fastapi import APIRouter, Depends, Query
+from app.services.proxy_service import ProxyService
+from app.services.scheduler_service import SchedulerService
+from app.models.schemas import ProxyListRequest, BatchDeleteRequest
+from app.api.deps import get_proxy_service, get_scheduler_service
+from app.api.common import success_response, error_response, format_proxy
+from app.core.log import logger
+
+router = APIRouter(prefix="/api/proxies", tags=["proxies"])
+
+
+@router.get("/stats")
+async def get_stats(
+    proxy_service: ProxyService = Depends(get_proxy_service),
+    scheduler_service: SchedulerService = Depends(get_scheduler_service),
+):
+    try:
+        stats = await proxy_service.get_stats()
+        stats["scheduler_running"] = scheduler_service.running
+        return success_response("获取统计信息成功", stats)
+    except Exception as e:
+        logger.error(f"Get stats failed: {e}")
+        return error_response("获取统计信息失败", 500)
+
+
+@router.post("")
+async def list_proxies(
+    request: ProxyListRequest,
+    service: ProxyService = Depends(get_proxy_service),
+):
+    try:
+        proxies, total = await service.list_proxies(
+            page=request.page,
+            page_size=request.page_size,
+            protocol=request.protocol,
+            min_score=request.min_score,
+            max_score=request.max_score,
+            sort_by=request.sort_by,
+            sort_order=request.sort_order,
+        )
+        return success_response(
+            "获取代理列表成功",
+            {
+                "list": [format_proxy(p) for p in proxies],
+                "total": total,
+                "page": request.page,
+                "page_size": request.page_size,
+            },
+        )
+    except Exception as e:
+        logger.error(f"List proxies failed: {e}")
+        return error_response("获取代理列表失败", 500)
+
+
+@router.get("/random")
+async def get_random_proxy(service: ProxyService = Depends(get_proxy_service)):
+    try:
+        proxy = await service.get_random_proxy()
+        if not proxy:
+            return error_response("没有找到可用的代理", 404)
+        return success_response("获取随机代理成功", format_proxy(proxy))
+    except Exception as e:
+        logger.error(f"Get random proxy failed: {e}")
+        return error_response("获取随机代理失败", 500)
+
+
+@router.get("/export/{fmt}")
+async def export_proxies(
+    fmt: str,
+    protocol: Optional[str] = None,
+    limit: int = Query(default=10000, ge=1, le=100000),
+    service: ProxyService = Depends(get_proxy_service),
+):
+    if fmt not in ("csv", "txt", "json"):
+        return error_response("不支持的导出格式", 400)
+
+    from fastapi.responses import StreamingResponse
+
+    media_types = {"csv": "text/csv", "txt": "text/plain", "json": "application/json"}
+
+    async def generate():
+        async for chunk in service.export_proxies(fmt, protocol, limit):
+            yield chunk
+
+    return StreamingResponse(
+        generate(),
+        media_type=media_types[fmt],
+        headers={"Content-Disposition": f"attachment; filename=proxies.{fmt}"},
+    )
+
+
+@router.delete("/{ip}/{port}")
+async def delete_proxy(ip: str, port: int, service: ProxyService = Depends(get_proxy_service)):
+    try:
+        await service.delete_proxy(ip, port)
+        return success_response("删除代理成功")
+    except Exception as e:
+        logger.error(f"Delete proxy failed: {e}")
+        return error_response("删除代理失败", 500)
+
+
+@router.post("/batch-delete")
+async def batch_delete(
+    request: BatchDeleteRequest,
+    service: ProxyService = Depends(get_proxy_service),
+):
+    try:
+        proxies = [(item.ip, item.port) for item in request.proxies]
+        deleted = await service.batch_delete(proxies)
+        return success_response(f"批量删除 {deleted} 个代理成功", {"deleted_count": deleted})
+    except Exception as e:
+        logger.error(f"Batch delete failed: {e}")
+        return error_response("批量删除失败", 500)
+
+
+@router.delete("/clean-invalid")
+async def clean_invalid(service: ProxyService = Depends(get_proxy_service)):
+    try:
+        count = await service.clean_invalid()
+        return success_response(f"清理了 {count} 个无效代理", {"deleted_count": count})
+    except Exception as e:
+        logger.error(f"Clean invalid failed: {e}")
+        return error_response("清理无效代理失败", 500)