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/DnsManagerUser.php

@@ -0,0 +1,28 @@
+<?php
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Factories\HasFactory;
+use Illuminate\Database\Eloquent\Model;
+
+class DnsManagerUser extends Model
+{
+    use HasFactory;
+
+    protected $table = 'dns_domain_user';
+
+    protected $fillable = [
+        'domain_id',
+        'user_id',
+    ];
+
+    public function customer()
+    {
+        return $this->belongsTo(Customer::class, 'user_id', 'id');
+    }
+
+    public function domain()
+    {
+        return $this->belongsTo(DnsDomain::class, 'domain_id', 'id');
+    }
+}