feat: Add DNS management resources and importer

- Implemented DomainCollection, DomainDetailResource, DomainNSCollection, DomainNSResource, and DomainResource for handling DNS domain and record data.
- Created VpsServiceCollection and VpsServiceResource for VPS service management.
- Added DnsManagerNS and DnsManagerUser models to represent DNS records and user associations.
- Developed AdminZoneDnsSqlImporter for importing DNS data from SQL dumps, including customer and DNS domain records.
- Added migration scripts to update the customers table with new fields and sync foreign key references for DNS tables.
- Created a migration preview document outlining the mapping and schema changes for the admin zone DNS import.

app/Models/DnsDomain.php

@@ -30,11 +30,21 @@ class DnsDomain extends Model
         return $this->belongsToMany(Customer::class, 'dns_domain_user', 'domain_id', 'user_id')->withTimestamps();
     }
 
+    public function users()
+    {
+        return $this->customer();
+    }
+
     public function server()
     {
         return $this->belongsTo(DnsServer::class, 'dns_manager_server_id', 'id');
     }
 
+    public function ns()
+    {
+        return $this->hasMany(DnsManagerNS::class, 'dns_manager_domain_id', 'id');
+    }
+
     public function record()
     {
         return $this->hasMany(DnsRecord::class, 'dns_manager_domain_id', 'id');