feat: Add Discord alert webhook, ContactCategory enum, form request

- Added Discord alert webhook URL to .env.example
- Created ContactCategory enum with humanReadable method
- Implemented ContactSubmissionRequest form request
- Added ContactSubmission model with fillable and casts properties
- Included configurations for Discord alerts and honeypot protection

app/Enums/ContactCategory.php

@@ -0,0 +1,23 @@
+<?php
+
+namespace App\Enums;
+
+enum ContactCategory: string
+{
+    case Question = 'question';
+    case Advertising = 'advertising';
+    case BugReport = 'bug_report';
+    case Feedback = 'feedback';
+    case Other = 'other';
+
+    public function humanReadable(): string
+    {
+        return match ($this) {
+            ContactCategory::Question => 'Question',
+            ContactCategory::Advertising => 'Advertising',
+            ContactCategory::BugReport => 'Bug Report',
+            ContactCategory::Feedback => 'Feedback',
+            ContactCategory::Other => 'Other',
+        };
+    }
+}