全面清理冗余与过度分层

后端优化：
- 合并 api/routes/stats.py 到 api/routes/proxies.py，统计接口变更为 /api/proxies/stats
- 内联 services/settings_service.py：settings.py 和 scheduler.py 直接使用 SettingsRepository
- 简化 repositories/proxy_repo.py：提取 _row_to_proxy 辅助函数，消除重复构造代码
- 更新 api/lifespan.py 和 api/deps.py，移除对 settings_service 的依赖
- 从 requirements.txt 移除 websockets 依赖（已废弃的 WebSocket 功能残留）

前端适配：
- 更新 frontend/src/api/index.js：stats 接口路径同步为 /api/proxies/stats
- 清理 api/index.js 中未使用的 createRequestConfig 和多余 JSDoc 注释

脚本优化：
- 移除 script/stop.bat 末尾的 pause，避免自动化调用时挂起

api/routes/settings.py

@@ -1,11 +1,12 @@
 """设置相关路由"""
-from fastapi import APIRouter, Depends
-from services.settings_service import SettingsService
+from fastapi import APIRouter
+from core.db import get_db
+from repositories.settings_repo import SettingsRepository
 from models.schemas import SettingsSchema
-from api.deps import get_settings_service
 from core.log import logger
 
 router = APIRouter(prefix="/api/settings", tags=["settings"])
+settings_repo = SettingsRepository()
 
 
 def success_response(message: str, data=None):
@@ -17,9 +18,10 @@ def error_response(message: str, code: int = 500):
 
 
 @router.get("")
-async def get_settings(service: SettingsService = Depends(get_settings_service)):
+async def get_settings():
     try:
-        settings = await service.get_settings()
+        async with get_db() as db:
+            settings = await settings_repo.get_all(db)
         return success_response("获取设置成功", settings)
     except Exception as e:
         logger.error(f"Get settings failed: {e}")
@@ -27,12 +29,10 @@ async def get_settings(service: SettingsService = Depends(get_settings_service))
 
 
 @router.post("")
-async def save_settings(
-    request: SettingsSchema,
-    service: SettingsService = Depends(get_settings_service),
-):
+async def save_settings(request: SettingsSchema):
     try:
-        success = await service.save_settings(request)
+        async with get_db() as db:
+            success = await settings_repo.save(db, request.model_dump())
         if not success:
             return error_response("保存设置失败")
         return success_response("保存设置成功", request.model_dump())