feat(admin): 管理端在线监控 + 好友关系管理后端

- admin/service/online_service.go: 在线用户列表/计数
- admin/controller/online_controller.go: GET /admin/online/users|count
- admin/service/contact_manage_service.go: 好友关系分页查询/管理员删除
- admin/controller/contact_manage_controller.go: GET|DELETE /admin/contacts
- 更新 admin router/provider/wire 集成新控制器

Made-with: Cursor

backend/go-service/app/admin/service/online_service.go

@@ -0,0 +1,26 @@
+package service
+
+import (
+	"context"
+
+	wsApp "github.com/echochat/backend/app/ws"
+	"github.com/echochat/backend/pkg/logs"
+)
+
+type OnlineManageService struct {
+	onlineService *wsApp.OnlineService
+}
+
+func NewOnlineManageService(onlineService *wsApp.OnlineService) *OnlineManageService {
+	return &OnlineManageService{onlineService: onlineService}
+}
+
+func (s *OnlineManageService) GetOnlineUsers(ctx context.Context) ([]int64, error) {
+	funcName := "service.online_manage_service.GetOnlineUsers"
+	logs.Debug(ctx, funcName, "获取在线用户列表")
+	return s.onlineService.GetOnlineUserIDs(ctx)
+}
+
+func (s *OnlineManageService) GetOnlineCount(ctx context.Context) (int64, error) {
+	return s.onlineService.GetOnlineCount(ctx)
+}