refactor: 前后端目录结构模块化 + v2 优化移植与缺陷修复

前端:
- src/srv/api → src/api，按域分文件夹(auth/cluster/host/storage/deployment/collector)
- 新增 http.ts 引擎(http.get/post/put/delete)，域模块改用语义化调用
- index.html 增加 favicon(匹配应用 logo 的 emerald + Activity 脉冲)

后端分层增强(保留包名):
- 新增 repository/：从 models 拆出 JsonDB 持久化层(InitDB/GetDB/Shutdown/RequestSave)
- 新增 dto/：从 controllers 抽出各域请求契约(带 binding 校验)
- 新增 pkg/crypto、pkg/jwt：从 utils 拆出安全原语(外部 jwt 别名 jwtv5 避免冲突)
- models 只留领域实体 + sanitizer；utils 只留 gin/应用相关(response/errors)

v2 优化移植与缺陷修复:
- 移植密钥分离/SSH TOFU/并发写安全/Loki 生产级配置/Docker 加固
- 修复 deployment.go 并发丢更新、Helm values 重复键、EncryptField 哨兵、loki-gateway 端点等审计缺陷
- 实现真正的优雅关停(main.go http.Server + signal + repository.Shutdown)
- 修复登录契约:后端返回 accessToken，前端 auth.ts/Login.tsx 对齐
- 补 crypto/jwt/repository 单元测试(含并发写回归)

验证: go build/vet/test 全绿；npm run build 通过；登录→鉴权→优雅关停冒烟通过

Co-Authored-By: Claude <noreply@anthropic.com>

backend/controllers/host.go

@@ -1,7 +1,9 @@
 package controllers
 
 import (
+	"lokideploy/dto"
 	"lokideploy/models"
+	"lokideploy/pkg/crypto"
 	"lokideploy/services"
 	"lokideploy/utils"
 
@@ -16,22 +18,8 @@ func NewHostController() *HostController {
 	return &HostController{service: services.NewHostService()}
 }
 
-type CreateHostRequest struct {
-	Name       string `json:"name" binding:"required"`
-	HostIP     string `json:"hostIP" binding:"required"`
-	Port       int    `json:"port"`
-	User       string `json:"user" binding:"required"`
-	AuthType   string `json:"authType" binding:"required,oneof=password key"`
-	Password   string `json:"password"`
-	PrivateKey string `json:"privateKey"`
-	KeyPhrase  string `json:"keyPhrase"`
-	OS         string `json:"os"`
-	Arch       string `json:"arch"`
-	Labels     string `json:"labels"`
-}
-
 func (ctrl *HostController) Create(c *gin.Context) {
-	var req CreateHostRequest
+	var req dto.CreateHostRequest
 	if !utils.BindAndValidate(c, &req) {
 		return
 	}
@@ -125,7 +113,7 @@ func (ctrl *HostController) GetInfo(c *gin.Context) {
 
 	password := host.Password
 	if len(password) > 4 && password[:4] == "ENC:" {
-		password, _ = utils.Decrypt(password[4:])
+		password, _ = crypto.Decrypt(password[4:])
 	}
 
 	client, err := services.NewSSHClient(host.HostIP, host.Port, host.User, password)