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/handler/role_handler.go

@@ -202,3 +202,128 @@ func (h *RoleHandler) handleError(c *gin.Context, err error) {
 		})
 	}
 }
+
+// GetRoleDetail 获取角色详情
+// GET /api/v1/admin/roles/:name
+func (h *RoleHandler) GetRoleDetail(c *gin.Context) {
+	name := c.Param("name")
+	if name == "" {
+		c.JSON(http.StatusBadRequest, gin.H{
+			"code":    "BAD_REQUEST",
+			"message": "缺少角色名称",
+		})
+		return
+	}
+
+	detail, err := h.roleService.GetRoleDetail(c.Request.Context(), name)
+	if err != nil {
+		h.handleError(c, err)
+		return
+	}
+
+	c.JSON(http.StatusOK, gin.H{
+		"data": detail,
+	})
+}
+
+// GetRolePermissions 获取角色权限
+// GET /api/v1/admin/roles/:name/permissions
+func (h *RoleHandler) GetRolePermissions(c *gin.Context) {
+	name := c.Param("name")
+	if name == "" {
+		c.JSON(http.StatusBadRequest, gin.H{
+			"code":    "BAD_REQUEST",
+			"message": "缺少角色名称",
+		})
+		return
+	}
+
+	permissions, err := h.roleService.GetRolePermissions(c.Request.Context(), name)
+	if err != nil {
+		h.handleError(c, err)
+		return
+	}
+
+	c.JSON(http.StatusOK, gin.H{
+		"data": permissions,
+	})
+}
+
+// GetAllPermissions 获取所有权限定义
+// GET /api/v1/admin/permissions
+func (h *RoleHandler) GetAllPermissions(c *gin.Context) {
+	permissions, err := h.roleService.GetAllPermissions(c.Request.Context())
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{
+			"code":    "INTERNAL_ERROR",
+			"message": "获取权限列表失败",
+		})
+		return
+	}
+
+	c.JSON(http.StatusOK, gin.H{
+		"data": permissions,
+	})
+}
+
+// UpdateRolePermissionsRequest 更新角色权限请求
+type UpdateRolePermissionsRequest struct {
+	Permissions []PermissionInput `json:"permissions" binding:"required"`
+}
+
+// PermissionInput 权限输入
+type PermissionInput struct {
+	Resource string `json:"resource" binding:"required"`
+	Action   string `json:"action" binding:"required"`
+}
+
+// UpdateRolePermissions 更新角色权限
+// PUT /api/v1/admin/roles/:name/permissions
+func (h *RoleHandler) UpdateRolePermissions(c *gin.Context) {
+	name := c.Param("name")
+	if name == "" {
+		c.JSON(http.StatusBadRequest, gin.H{
+			"code":    "BAD_REQUEST",
+			"message": "缺少角色名称",
+		})
+		return
+	}
+
+	var req UpdateRolePermissionsRequest
+	if err := c.ShouldBindJSON(&req); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{
+			"code":    "BAD_REQUEST",
+			"message": "请求参数错误",
+		})
+		return
+	}
+
+	// 转换权限格式
+	var permissions []service.Permission
+	for _, p := range req.Permissions {
+		permissions = append(permissions, service.Permission{
+			Resource: p.Resource,
+			Action:   p.Action,
+		})
+	}
+
+	err := h.roleService.UpdateRolePermissions(c.Request.Context(), name, permissions)
+	if err != nil {
+		h.handleError(c, err)
+		return
+	}
+
+	// 返回更新后的角色信息
+	detail, err := h.roleService.GetRoleDetail(c.Request.Context(), name)
+	if err != nil {
+		c.JSON(http.StatusOK, gin.H{
+			"message": "权限更新成功",
+		})
+		return
+	}
+
+	c.JSON(http.StatusOK, gin.H{
+		"message": "权限更新成功",
+		"data":    detail,
+	})
+}