feat(admin): add comprehensive admin management system

- Add admin handlers and services for users, posts, comments, groups, and dashboard
- Implement role permission management with ability to view and update permissions
- Add database seeding for roles and Casbin permission policies
- Upgrade Casbin from v2 to v3 with GORM adapter for persistent policy storage
- Add admin-specific repository methods with filtering and pagination
- Register new admin API routes under /api/v1/admin/*

internal/service/casbin_service.go

@@ -9,7 +9,7 @@ import (
 	"carrot_bbs/internal/config"
 	"carrot_bbs/internal/repository"
 
-	"github.com/casbin/casbin/v2"
+	"github.com/casbin/casbin/v3"
 )
 
 // CasbinService Casbin 权限服务接口
@@ -43,6 +43,15 @@ type CasbinService interface {
 
 	// ClearCache 清除权限缓存
 	ClearCache(ctx context.Context) error
+
+	// GetPermissionsForRole 获取角色的所有权限
+	GetPermissionsForRole(ctx context.Context, role string) ([][]string, error)
+
+	// UpdatePermissionsForRole 更新角色的权限（先删除所有权限，再添加新权限）
+	UpdatePermissionsForRole(ctx context.Context, role string, permissions [][]string) error
+
+	// GetAllPermissions 获取系统中所有权限定义
+	GetAllPermissions(ctx context.Context) [][]string
 }
 
 type casbinService struct {
@@ -223,3 +232,34 @@ func (s *casbinService) clearUserCache(ctx context.Context, userID string) error
 	}
 	return nil
 }
+
+func (s *casbinService) GetPermissionsForRole(ctx context.Context, role string) ([][]string, error) {
+	return s.enforcer.GetPermissionsForUser(role)
+}
+
+func (s *casbinService) UpdatePermissionsForRole(ctx context.Context, role string, permissions [][]string) error {
+	// 先删除该角色的所有权限
+	_, err := s.enforcer.DeletePermissionsForUser(role)
+	if err != nil {
+		return err
+	}
+
+	// 添加新权限
+	for _, perm := range permissions {
+		if len(perm) >= 2 {
+			resource := perm[0]
+			action := perm[1]
+			if _, err := s.enforcer.AddPolicy(role, resource, action); err != nil {
+				return err
+			}
+		}
+	}
+
+	// 清除缓存
+	return s.ClearCache(ctx)
+}
+
+func (s *casbinService) GetAllPermissions(ctx context.Context) [][]string {
+	permissions, _ := s.enforcer.GetPolicy()
+	return permissions
+}