fix(transfers): add missing marriage_date column to transfer_requests

The column was in the model's fillable but never had a migration. Causes
'Column not found' error when storing female child separation requests.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

database/migrations/Phase_98_006_add_marriage_date_to_transfer_requests.php

+<?php
+declare(strict_types=1);
+
+return [
+    'up' => function (\App\Core\Database $db): void {
+        $exists = $db->selectOne(
+            "SELECT 1 FROM information_schema.COLUMNS
+              WHERE table_schema = DATABASE() AND table_name = 'transfer_requests' AND column_name = 'marriage_date'",
+            []
+        );
+        if (!$exists) {
+            $db->raw("ALTER TABLE transfer_requests ADD COLUMN marriage_date DATE NULL DEFAULT NULL AFTER work_date");
+        }
+    },
+    'down' => "ALTER TABLE transfer_requests DROP COLUMN IF EXISTS marriage_date;",
+];