Add gold credit feature gated by SuperAdmin enable_gold_credit.

Port tables, APIs, and overdue cron from goldali, default the flag off, and keep customer routes behind auth.

Co-authored-by: Cursor <cursoragent@cursor.com>

app/Models/GoldCreditRequest.php

@@ -0,0 +1,33 @@
+<?php
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\BelongsTo;
+
+class GoldCreditRequest extends Model
+{
+    protected $fillable = [
+        'customer_id',
+        'requested_gold',
+        'requested_months',
+        'note',
+        'status',
+        'admin_note',
+        'gold_credit_id',
+    ];
+
+    protected $casts = [
+        'requested_gold' => 'float',
+    ];
+
+    public function customer(): BelongsTo
+    {
+        return $this->belongsTo(Customer::class);
+    }
+
+    public function goldCredit(): BelongsTo
+    {
+        return $this->belongsTo(GoldCredit::class);
+    }
+}