feat(audit): F1+F2 告警静默规则标记完成 + 审计日志CSV导出实现

F1 告警静默规则 [done]:
- 后端 alert_silence.go: CRUD + Toggle (onetime/daily/weekly 三模式)
- 告警引擎 isSilenced 集成 (alert_engine.go)
- 前端 SilenceRuleTab + SilenceDialog
- 路由 /alerts/silences 已注册

F2 审计日志导出 [done]:
- 重写 ExportAuditLogs: 真正的 CSV 导出 (encoding/csv + UTF-8 BOM)
- 支持 module/action/username/startTime/endTime 筛选
- 导出限制 10000 条防溢出，自动记录审计日志
- JSON 格式向后兼容 (format=json)
- 前端 exportLogs 传递查询参数

同时包含累积的前期工作:
- 目录重构 internal/ -> controller/model/router (v0.55-v0.57)
- 后端分层架构 dto/repository/service/utils
- 审计模块全功能 (终端审计/操作审计/登录日志)
- asciicast v2 录制格式
- SFTP 文件浏览器
- StatStrip 紧凑统计条
- 在线会话自动刷新
- LiveMonitor WebSocket 诊断修复

验证: go build ✅ | npm run build ✅ | Docker 部署 ✅ | 10 回归端点 ✅ | CSV 导出 ✅ | 静默 CRUD ✅

backend/middleware/auth.go

@@ -0,0 +1,139 @@
+package middleware
+
+import (
+	"net/http"
+	"strings"
+	"time"
+
+	"ezops/config"
+	"ezops/model"
+
+	"github.com/gin-gonic/gin"
+	"github.com/golang-jwt/jwt/v5"
+)
+
+// JWTClaims JWT声明
+type JWTClaims struct {
+	UserID   uint   `json:"user_id"`
+	Username string `json:"username"`
+	IsAdmin  bool   `json:"is_admin"`
+	jwt.RegisteredClaims
+}
+
+// GenerateToken 生成JWT令牌
+func GenerateToken(user *model.User, cfg *config.JWTConfig) (string, error) {
+	claims := JWTClaims{
+		UserID:   user.ID,
+		Username: user.Username,
+		IsAdmin:  user.IsAdmin,
+		RegisteredClaims: jwt.RegisteredClaims{
+			ExpiresAt: jwt.NewNumericDate(time.Now().Add(time.Duration(cfg.ExpireHour) * time.Hour)),
+			IssuedAt:  jwt.NewNumericDate(time.Now()),
+			Issuer:    "ezops",
+		},
+	}
+
+	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
+	return token.SignedString([]byte(cfg.Secret))
+}
+
+// JWTAuth JWT认证中间件
+func JWTAuth(cfg *config.JWTConfig) gin.HandlerFunc {
+	return func(c *gin.Context) {
+		authHeader := c.GetHeader("Authorization")
+		// Also allow token via query param for file downloads
+		if authHeader == "" {
+			if token := c.Query("token"); token != "" {
+				authHeader = "Bearer " + token
+			}
+		}
+		if authHeader == "" {
+			c.JSON(http.StatusUnauthorized, model.Response{
+				Code:    401,
+				Message: "未提供认证令牌",
+			})
+			c.Abort()
+			return
+		}
+
+		parts := strings.SplitN(authHeader, " ", 2)
+		if !(len(parts) == 2 && parts[0] == "Bearer") {
+			c.JSON(http.StatusUnauthorized, model.Response{
+				Code:    401,
+				Message: "认证令牌格式错误",
+			})
+			c.Abort()
+			return
+		}
+
+		tokenString := parts[1]
+		token, err := jwt.ParseWithClaims(tokenString, &JWTClaims{}, func(token *jwt.Token) (interface{}, error) {
+			return []byte(cfg.Secret), nil
+		})
+
+		if err != nil {
+			c.JSON(http.StatusUnauthorized, model.Response{
+				Code:    401,
+				Message: "无效的认证令牌: " + err.Error(),
+			})
+			c.Abort()
+			return
+		}
+
+		if claims, ok := token.Claims.(*JWTClaims); ok && token.Valid {
+			c.Set("userID", claims.UserID)
+			c.Set("username", claims.Username)
+			c.Set("isAdmin", claims.IsAdmin)
+			c.Next()
+		} else {
+			c.JSON(http.StatusUnauthorized, model.Response{
+				Code:    401,
+				Message: "无效的认证令牌",
+			})
+			c.Abort()
+		}
+	}
+}
+
+// AdminAuth 管理员认证中间件
+func AdminAuth() gin.HandlerFunc {
+	return func(c *gin.Context) {
+		isAdmin, exists := c.Get("isAdmin")
+		if !exists || !isAdmin.(bool) {
+			c.JSON(http.StatusForbidden, model.Response{
+				Code:    403,
+				Message: "需要管理员权限",
+			})
+			c.Abort()
+			return
+		}
+		c.Next()
+	}
+}
+
+// GetUserID 获取当前用户ID
+func GetUserID(c *gin.Context) uint {
+	userID, exists := c.Get("userID")
+	if !exists {
+		return 0
+	}
+	return userID.(uint)
+}
+
+// GetUsername 获取当前用户名
+func GetUsername(c *gin.Context) string {
+	username, exists := c.Get("username")
+	if !exists {
+		return ""
+	}
+	return username.(string)
+}
+
+// GetIsAdmin 获取是否为管理员
+func GetIsAdmin(c *gin.Context) bool {
+	isAdmin, exists := c.Get("isAdmin")
+	if !exists {
+		return false
+	}
+	return isAdmin.(bool)
+}