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/api_key.go

@@ -0,0 +1,29 @@
+package mdb
+
+import "github.com/dromara/carbon/v2"
+
+const (
+	ApiKeyStatusEnable  = 1
+	ApiKeyStatusDisable = 2
+)
+
+// ApiKey stores a universal merchant credential (PID + secret) that is
+// valid for both EPAY and GMPAY payment flows. Identification at
+// request time is always by PID; the gateway flow is chosen by the
+// route (not by any property of the row).
+type ApiKey struct {
+	Name        string `gorm:"column:name;size:128" json:"name" example:"My API Key"`
+	Pid         string `gorm:"column:pid;size:128;uniqueIndex:api_keys_pid_uindex" json:"pid" example:"1000"`
+	SecretKey   string `gorm:"column:secret_key;size:255" json:"-"`
+	IpWhitelist string `gorm:"column:ip_whitelist;type:text" json:"ip_whitelist" example:"192.168.1.0/24,10.0.0.1"`
+	NotifyUrl   string `gorm:"column:notify_url;size:512" json:"notify_url" example:"https://example.com/notify"`
+	// 状态 1=启用 2=禁用
+	Status     int         `gorm:"column:status;default:1" json:"status" enums:"1,2" example:"1"`
+	CallCount  int64       `gorm:"column:call_count;default:0" json:"call_count" example:"342"`
+	LastUsedAt carbon.Time `gorm:"column:last_used_at" json:"last_used_at" example:"2026-04-16 12:00:00"`
+	BaseModel
+}
+
+func (a *ApiKey) TableName() string {
+	return "api_keys"
+}