Send signed outgoing webhooks

Fed by the records themselves, delivered only to public HTTPS addresses
checked at every attempt, retried, and switched off after repeated failures.
A submitter's details travel only to webhooks that opted into them.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

app/Models/WebhookDelivery.php

@@ -0,0 +1,40 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Attributes\Fillable;
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\BelongsTo;
+
+/**
+ * One attempt to tell a webhook about one event, and how it went.
+ */
+#[Fillable(['uuid', 'event', 'payload', 'status', 'attempts', 'response_status', 'error', 'delivered_at'])]
+class WebhookDelivery extends Model
+{
+    public const PENDING = 'pending';
+
+    public const SUCCEEDED = 'succeeded';
+
+    public const FAILED = 'failed';
+
+    protected function casts(): array
+    {
+        return [
+            'payload' => 'array',
+            'attempts' => 'integer',
+            'response_status' => 'integer',
+            'delivered_at' => 'datetime',
+        ];
+    }
+
+    /**
+     * @return BelongsTo<Webhook, $this>
+     */
+    public function webhook(): BelongsTo
+    {
+        return $this->belongsTo(Webhook::class);
+    }
+}