Initial commit: DDNS service with NIC V2 protocol support

Features:
- Token-based subdomain claiming
- NIC V2 (DynDNS2) protocol implementation
- Technitium DNS integration
- Rate limiting (10 req/min IP, 1 req/min token)
- Web UI for space claiming
- Docker/Docker Compose support
- Compatible with UniFi, pfSense, EdgeRouter

Module: git.dws.rip/DWS/dyn

internal/models/space.go

@@ -0,0 +1,35 @@
+package models
+
+import (
+	"time"
+)
+
+type Space struct {
+	Token     string    `json:"token" db:"token"`
+	Subdomain string    `json:"subdomain" db:"subdomain"`
+	LastIP    string    `json:"last_ip" db:"last_ip"`
+	UpdatedAt time.Time `json:"updated_at" db:"updated_at"`
+	CreatedAt time.Time `json:"created_at" db:"created_at"`
+}
+
+type CreateSpaceRequest struct {
+	Subdomain string `json:"subdomain" binding:"required,alphanumdash,min=3,max=63"`
+}
+
+type CreateSpaceResponse struct {
+	Token     string    `json:"token"`
+	Subdomain string    `json:"subdomain"`
+	FQDN      string    `json:"fqdn"`
+	CreatedAt time.Time `json:"created_at"`
+}
+
+type SpaceInfo struct {
+	Subdomain string    `json:"subdomain"`
+	LastIP    string    `json:"last_ip"`
+	UpdatedAt time.Time `json:"updated_at"`
+	CreatedAt time.Time `json:"created_at"`
+}
+
+func (s *Space) GetFQDN(zone string) string {
+	return s.Subdomain + "." + zone
+}