refactor: 将 DTO 文件从 internal/model 移动到 internal/model/dto 目录

- 移动 17 个 DTO 文件到 internal/model/dto/ 目录
- 更新所有 DTO 文件的 package 声明从 model 改为 dto
- 更新所有引用文件的 import 和类型引用
  - Handler 层：admin 和 h5 所有处理器
  - Service 层：所有业务服务
  - Routes 层：所有路由定义
  - Tests 层：单元测试和集成测试
- 清理未使用的 import 语句
- 验证：项目构建成功，测试编译通过，LSP 无错误

tests/integration/account_test.go

@@ -24,6 +24,7 @@ import (
 	"github.com/break/junhong_cmp_fiber/internal/bootstrap"
 	"github.com/break/junhong_cmp_fiber/internal/handler/admin"
 	"github.com/break/junhong_cmp_fiber/internal/model"
+	"github.com/break/junhong_cmp_fiber/internal/model/dto"
 	"github.com/break/junhong_cmp_fiber/internal/routes"
 	accountService "github.com/break/junhong_cmp_fiber/internal/service/account"
 	postgresStore "github.com/break/junhong_cmp_fiber/internal/store/postgres"
@@ -183,7 +184,7 @@ func TestAccountAPI_Create(t *testing.T) {
 	createTestAccount(t, env.db, rootAccount)
 
 	t.Run("成功创建平台账号", func(t *testing.T) {
-		reqBody := model.CreateAccountRequest{
+		reqBody := dto.CreateAccountRequest{
 			Username: "platform_user",
 			Phone:    "13800000001",
 			Password: "Password123",
@@ -221,7 +222,7 @@ func TestAccountAPI_Create(t *testing.T) {
 		createTestAccount(t, env.db, existingAccount)
 
 		// 尝试创建同名账号
-		reqBody := model.CreateAccountRequest{
+		reqBody := dto.CreateAccountRequest{
 			Username: "existing_user",
 			Phone:    "13800000003",
 			Password: "Password123",
@@ -242,7 +243,7 @@ func TestAccountAPI_Create(t *testing.T) {
 	})
 
 	t.Run("非root用户缺少parent_id时返回错误", func(t *testing.T) {
-		reqBody := model.CreateAccountRequest{
+		reqBody := dto.CreateAccountRequest{
 			Username: "no_parent_user",
 			Phone:    "13800000004",
 			Password: "Password123",
@@ -347,7 +348,7 @@ func TestAccountAPI_Update(t *testing.T) {
 
 	t.Run("成功更新账号", func(t *testing.T) {
 		newUsername := "updated_user"
-		reqBody := model.UpdateAccountRequest{
+		reqBody := dto.UpdateAccountRequest{
 			Username: &newUsername,
 		}
 
@@ -480,7 +481,7 @@ func TestAccountAPI_AssignRoles(t *testing.T) {
 	env.db.Create(testRole)
 
 	t.Run("成功分配角色", func(t *testing.T) {
-		reqBody := model.AssignRolesRequest{
+		reqBody := dto.AssignRolesRequest{
 			RoleIDs: []uint{testRole.ID},
 		}