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/config/config.go

@@ -0,0 +1,105 @@
+package config
+
+import (
+	"fmt"
+
+	"github.com/spf13/viper"
+	"go.uber.org/zap"
+)
+
+// Config 应用配置
+type Config struct {
+	Mode      string         `mapstructure:"mode"`
+	Port      string         `mapstructure:"port"`
+	LogLevel  string         `mapstructure:"log_level"`
+	Database  DatabaseConfig `mapstructure:"database"`
+	JWT       JWTConfig      `mapstructure:"jwt"`
+	Redis     RedisConfig    `mapstructure:"redis"`
+	Websocket WebsocketConfig `mapstructure:"websocket"`
+}
+
+// DatabaseConfig 数据库配置
+type DatabaseConfig struct {
+	Driver   string `mapstructure:"driver"`
+	Host     string `mapstructure:"host"`
+	Port     int    `mapstructure:"port"`
+	User     string `mapstructure:"user"`
+	Password string `mapstructure:"password"`
+	DBName   string `mapstructure:"dbname"`
+	Charset  string `mapstructure:"charset"`
+	MaxConn  int    `mapstructure:"max_conn"`
+	MaxIdle  int    `mapstructure:"max_idle"`
+}
+
+// JWTConfig JWT配置
+type JWTConfig struct {
+	Secret     string `mapstructure:"secret"`
+	ExpireHour int    `mapstructure:"expire_hour"`
+}
+
+// RedisConfig Redis配置
+type RedisConfig struct {
+	Driver   string `mapstructure:"driver"`   // redka (内嵌) / redis (外部)
+	Host     string `mapstructure:"host"`
+	Port     int    `mapstructure:"port"`
+	Password string `mapstructure:"password"`
+	DB       int    `mapstructure:"db"`
+}
+
+// WebsocketConfig WebSocket配置
+type WebsocketConfig struct {
+	ReadBufferSize  int `mapstructure:"read_buffer_size"`
+	WriteBufferSize int `mapstructure:"write_buffer_size"`
+}
+
+// Load 加载配置
+func Load() *Config {
+	viper.SetConfigName("config")
+	viper.SetConfigType("yaml")
+	viper.AddConfigPath("./configs")
+	viper.AddConfigPath(".")
+
+	// 设置默认值
+	viper.SetDefault("mode", "development")
+	viper.SetDefault("port", "8080")
+	viper.SetDefault("log_level", "info")
+	viper.SetDefault("database.driver", "sqlite")
+	viper.SetDefault("database.dbname", "data/aiops.db")
+	viper.SetDefault("database.host", "localhost")
+	viper.SetDefault("database.port", 3306)
+	viper.SetDefault("database.charset", "utf8mb4")
+	viper.SetDefault("database.max_conn", 100)
+	viper.SetDefault("database.max_idle", 10)
+	viper.SetDefault("jwt.expire_hour", 24)
+	viper.SetDefault("redis.host", "localhost")
+	viper.SetDefault("redis.port", 6379)
+	viper.SetDefault("redis.driver", "redka")
+	viper.SetDefault("websocket.read_buffer_size", 1024)
+	viper.SetDefault("websocket.write_buffer_size", 1024)
+
+	// 读取环境变量
+	viper.AutomaticEnv()
+
+	var cfg Config
+	if err := viper.ReadInConfig(); err != nil {
+		zap.L().Warn("config file not found, using defaults", zap.Error(err))
+	}
+
+	if err := viper.Unmarshal(&cfg); err != nil {
+		zap.L().Fatal("failed to unmarshal config", zap.Error(err))
+	}
+
+	return &cfg
+}
+
+// DSN 返回数据库连接字符串
+func (d *DatabaseConfig) DSN() string {
+	if d.Driver == "mysql" {
+		return fmt.Sprintf("%s:%s@tcp(%s:%d)/%s?charset=%s&parseTime=True&loc=Local",
+			d.User, d.Password, d.Host, d.Port, d.DBName, d.Charset)
+	}
+	if d.Driver == "sqlite" {
+		return d.DBName
+	}
+	return ""
+}