feat: LokiDeploy 初始提交 - 轻量级 K8s Loki 部署平台

Go(Gin) + React(Vite + shadcn/ui + Tailwind) 前后端分离，全中文 UI

- 集群管理：Kubeconfig / Token 双接入，kubectl + helm 部署
- 主机管理：SSH 密钥 / 密码双认证，CPU/内存/磁盘使用率监控，SSH 错误中文友好提示
- 存储配置、部署管理、系统设置
- Docker 镜像内置 kubectl + helm，开箱即用
- run.sh 一键启停（start/stop/restart/status）

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

backend/middleware/jwt.go

@@ -0,0 +1,70 @@
+package middleware
+
+import (
+	"strings"
+
+	"lokideploy/utils"
+
+	"github.com/gin-gonic/gin"
+)
+
+func JWTAuth() gin.HandlerFunc {
+	return func(c *gin.Context) {
+		authHeader := c.GetHeader("Authorization")
+		if authHeader == "" {
+			utils.Unauthorized(c, "missing authorization header")
+			c.Abort()
+			return
+		}
+
+		parts := strings.SplitN(authHeader, " ", 2)
+		if len(parts) != 2 || strings.ToLower(parts[0]) != "bearer" {
+			utils.Unauthorized(c, "invalid authorization header format")
+			c.Abort()
+			return
+		}
+
+		claims, err := utils.ParseToken(parts[1])
+		if err != nil {
+			utils.Unauthorized(c, "invalid or expired token")
+			c.Abort()
+			return
+		}
+
+		c.Set("user", claims)
+		c.Set("userId", claims.UserID)
+		c.Set("username", claims.Username)
+		c.Set("role", claims.Role)
+		c.Next()
+	}
+}
+
+func AdminAuth() gin.HandlerFunc {
+	return func(c *gin.Context) {
+		role, exists := c.Get("role")
+		if !exists || role != "admin" {
+			utils.Forbidden(c, "admin access required")
+			c.Abort()
+			return
+		}
+		c.Next()
+	}
+}
+
+func CORSMiddleware() gin.HandlerFunc {
+	return func(c *gin.Context) {
+		origin := c.GetHeader("Origin")
+		if origin == "" {
+			origin = "*"
+		}
+		c.Writer.Header().Set("Access-Control-Allow-Origin", origin)
+		c.Writer.Header().Set("Access-Control-Allow-Credentials", "true")
+		c.Writer.Header().Set("Access-Control-Allow-Headers", "Content-Type, Content-Length, Authorization, Accept, X-Requested-With")
+		c.Writer.Header().Set("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE, OPTIONS, PATCH")
+		if c.Request.Method == "OPTIONS" {
+			c.AbortWithStatus(204)
+			return
+		}
+		c.Next()
+	}
+}