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/contact_manage_service.go

@@ -0,0 +1,67 @@
+package service
+
+import (
+	"context"
+
+	"github.com/echochat/backend/app/contact/model"
+	"github.com/echochat/backend/pkg/logs"
+	"go.uber.org/zap"
+	"gorm.io/gorm"
+)
+
+type ContactManageService struct {
+	db *gorm.DB
+}
+
+func NewContactManageService(db *gorm.DB) *ContactManageService {
+	return &ContactManageService{db: db}
+}
+
+type AdminFriendship struct {
+	ID             int64  `json:"id"`
+	UserID         int64  `json:"user_id"`
+	UserUsername   string `json:"user_username"`
+	FriendID       int64  `json:"friend_id"`
+	FriendUsername string `json:"friend_username"`
+	Status         int    `json:"status"`
+	CreatedAt      string `json:"created_at"`
+}
+
+// GetAllFriendships 获取所有好友关系（分页）
+func (s *ContactManageService) GetAllFriendships(ctx context.Context, page, pageSize int) ([]AdminFriendship, int64, error) {
+	funcName := "service.contact_manage_service.GetAllFriendships"
+	logs.Debug(ctx, funcName, "管理端查询好友关系")
+
+	var total int64
+	s.db.WithContext(ctx).Model(&model.Friendship{}).Count(&total)
+
+	var results []AdminFriendship
+	offset := (page - 1) * pageSize
+	err := s.db.WithContext(ctx).
+		Table("contact_friendships f").
+		Select("f.id, f.user_id, u1.username as user_username, f.friend_id, u2.username as friend_username, f.status, TO_CHAR(f.created_at, 'YYYY-MM-DD HH24:MI:SS') as created_at").
+		Joins("JOIN auth_users u1 ON u1.id = f.user_id").
+		Joins("JOIN auth_users u2 ON u2.id = f.friend_id").
+		Order("f.created_at DESC").
+		Offset(offset).Limit(pageSize).
+		Scan(&results).Error
+
+	return results, total, err
+}
+
+// DeleteFriendship 管理员删除好友关系（双向删除）
+func (s *ContactManageService) DeleteFriendship(ctx context.Context, friendshipID int64) error {
+	funcName := "service.contact_manage_service.DeleteFriendship"
+	logs.Info(ctx, funcName, "管理员删除好友关系", zap.Int64("friendship_id", friendshipID))
+
+	var f model.Friendship
+	if err := s.db.WithContext(ctx).First(&f, friendshipID).Error; err != nil {
+		return err
+	}
+
+	return s.db.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
+		tx.Where("user_id = ? AND friend_id = ?", f.UserID, f.FriendID).Delete(&model.Friendship{})
+		tx.Where("user_id = ? AND friend_id = ?", f.FriendID, f.UserID).Delete(&model.Friendship{})
+		return nil
+	})
+}