refactor: 弹框架构重构 + 审核规则seed API + LDAP默认配置 + 全量初始数据

弹框架构:
- Layout header/sidebar z-[200] 隔离弹框层，弹框不再遮挡面包屑
- dialog.tsx 简化: 去掉 border/backdrop-blur，统一暗色主题变量
- ModalOverlay z-[100] 对齐 Radix Dialog overlay 层级
- EditInstanceDialog 同步 z-index 修复
- 修复 InstanceGroupPage/InstancePage/LdapConfigPage 缺失 import
- 修复 InstanceGroupPage 缺失 X icon import
- RedisDetailPage ModalOverlay 迁移为 FormDialog

审核规则:
- POST /audit-rules/seed/:dbType 初始化默认规则 (mysql 11/pg 7/redis 4/mongo 4)
- POST /audit-rules/:id/toggle 开关规则
- PUT /audit-rules/:id 编辑规则
- seed.go 启动时自动创建 26 条默认审核规则

LDAP 默认配置:
- seed.go 自动写入 9 条 LDAP 配置 (8.217.205.92:389, dc=opsx,dc=vip)
- 全新 DB 启动即就位，无需手动配置

backend/router/router.go

@@ -181,6 +181,9 @@ func Setup(r *gin.Engine) {
 
 		// Read-only resources
 		auth.GET("/audit-rules", handler.ListAuditRules)
+		auth.POST("/audit-rules/seed/:dbType", handler.SeedAuditRules)
+		auth.POST("/audit-rules/:id/toggle", handler.ToggleAuditRule)
+		auth.PUT("/audit-rules/:id", handler.UpdateAuditRule)
 		auth.GET("/announcements", handler.ListAnnouncements)
 		auth.GET("/query-histories", handler.ListQueryHistories)
 		// Notifications CRUD (replaces old channels/templates endpoints)