feat: add admin panel with multi-chain support and notification system

- Add full admin REST API: auth, API keys, chains, chain tokens, wallets,
  orders, RPC nodes, settings, dashboard stats, notifications
- Add JWT-based admin authentication and API key auth middleware
- Add multi-chain listeners: BSC, ETH, Polygon, Plasma, EVM WebSocket
- Add RPC node health check job with automatic failover
- Add Telegram notification channel for order events
- Add installer for first-run database initialization
- Add new DB models: admin_user, api_key, chain, chain_token,
  rpc_node, settings, notification_channel
- Add order statistics aggregation (daily/monthly/by-chain)
- Serve built admin SPA from embedded www/ assets
- Add comprehensive test coverage for all new features

src/model/mdb/admin_user.go

@@ -0,0 +1,21 @@
+package mdb
+
+import "github.com/dromara/carbon/v2"
+
+const (
+	AdminUserStatusEnable  = 1
+	AdminUserStatusDisable = 2
+)
+
+type AdminUser struct {
+	Username     string `gorm:"column:username;uniqueIndex:admin_users_username_uindex;size:64" json:"username" example:"admin"`
+	PasswordHash string `gorm:"column:password_hash;size:255" json:"-"`
+	// 状态 1=启用 2=禁用
+	Status      int         `gorm:"column:status;default:1" json:"status" enums:"1,2" example:"1"`
+	LastLoginAt carbon.Time `gorm:"column:last_login_at" json:"last_login_at" example:"2026-04-16 12:00:00"`
+	BaseModel
+}
+
+func (a *AdminUser) TableName() string {
+	return "admin_users"
+}