Initial baseline: LaraBlog core with plugin commerce surface.

Captures the current working tree after theme slots, ArticleAccess, and the payment / paid-content plugins so subsequent work has a reviewable git history.

app/Domain/Blog/ContentFormat.php

@@ -0,0 +1,29 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Domain\Blog;
+
+final class ContentFormat
+{
+    public const HTML = 'html';
+
+    public const MARKDOWN = 'markdown';
+
+    public static function all(): array
+    {
+        return [self::HTML, self::MARKDOWN];
+    }
+
+    public static function isValid(string $format): bool
+    {
+        return in_array($format, self::all(), true);
+    }
+
+    public static function normalize(?string $format, string $fallback = self::HTML): string
+    {
+        $format = strtolower(trim((string) $format));
+
+        return self::isValid($format) ? $format : $fallback;
+    }
+}