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

database/migrations/2024_02_24_162055_create_contact_submissions_table.php

@@ -0,0 +1,26 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class () extends Migration {
+    public function up(): void
+    {
+        Schema::create('contact_submissions', function (Blueprint $table) {
+            $table->id();
+            $table->string('name');
+            $table->string('email');
+            $table->string('discord')->nullable();
+            $table->enum('category', ['question', 'advertising', 'bug_report', 'feedback', 'other']);
+            $table->string('subject');
+            $table->text('message')->unique();
+            $table->timestamps();
+        });
+    }
+
+    public function down(): void
+    {
+        Schema::dropIfExists('contact_submissions');
+    }
+};