Add helpdesk import progress, category model, article metadata columns, and ticket pagination controls

app/Models/Category.php

@@ -0,0 +1,22 @@
+<?php
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\BelongsTo;
+use Illuminate\Database\Eloquent\Relations\HasMany;
+
+class Category extends Model
+{
+    protected $fillable = ['external_id', 'parent_id', 'name', 'slug'];
+
+    public function parent(): BelongsTo
+    {
+        return $this->belongsTo(self::class, 'parent_id');
+    }
+
+    public function children(): HasMany
+    {
+        return $this->hasMany(self::class, 'parent_id');
+    }
+}