添加代理节点功能，包括节点注册、心跳检测和配置获取，完善相关API路由和服务逻辑

atsf_server/model/node.go

@@ -0,0 +1,29 @@
+package model
+
+import "time"
+
+type Node struct {
+	ID             uint      `json:"id" gorm:"primaryKey"`
+	NodeID         string    `json:"node_id" gorm:"uniqueIndex;size:64;not null"`
+	Name           string    `json:"name" gorm:"size:128;not null"`
+	IP             string    `json:"ip" gorm:"size:64;not null"`
+	AgentVersion   string    `json:"agent_version" gorm:"size:64;not null"`
+	NginxVersion   string    `json:"nginx_version" gorm:"size:64"`
+	Status         string    `json:"status" gorm:"size:16;not null;default:'offline'"`
+	CurrentVersion string    `json:"current_version" gorm:"size:32"`
+	LastSeenAt     time.Time `json:"last_seen_at"`
+	LastError      string    `json:"last_error" gorm:"size:1024"`
+	CreatedAt      time.Time `json:"created_at"`
+	UpdatedAt      time.Time `json:"updated_at"`
+}
+
+func ListNodes() (nodes []*Node, err error) {
+	err = DB.Order("id desc").Find(&nodes).Error
+	return nodes, err
+}
+
+func GetNodeByNodeID(nodeID string) (*Node, error) {
+	node := &Node{}
+	err := DB.Where("node_id = ?", nodeID).First(node).Error
+	return node, err
+}