Add SealShare file sharing application with encryption, branding, auth, Docker, and Octane support

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/Http/Middleware/EnsureAdmin.php

@@ -0,0 +1,19 @@
+<?php
+
+namespace App\Http\Middleware;
+
+use Closure;
+use Illuminate\Http\Request;
+use Symfony\Component\HttpFoundation\Response;
+
+class EnsureAdmin
+{
+    public function handle(Request $request, Closure $next): Response
+    {
+        if (! $request->user() || ! $request->user()->is_admin) {
+            abort(403);
+        }
+
+        return $next($request);
+    }
+}