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/SecurityHeaders.php

@@ -0,0 +1,27 @@
+<?php
+
+namespace App\Http\Middleware;
+
+use Closure;
+use Illuminate\Http\Request;
+use Symfony\Component\HttpFoundation\Response;
+
+class SecurityHeaders
+{
+    /**
+     * Handle an incoming request.
+     *
+     * @param  \Closure(\Illuminate\Http\Request): (\Symfony\Component\HttpFoundation\Response)  $next
+     */
+    public function handle(Request $request, Closure $next): Response
+    {
+        $response = $next($request);
+
+        $response->headers->set('X-Content-Type-Options', 'nosniff');
+        $response->headers->set('X-Frame-Options', 'DENY');
+        $response->headers->set('Referrer-Policy', 'strict-origin-when-cross-origin');
+        $response->headers->set('Permissions-Policy', 'camera=(), microphone=(), geolocation=()');
+
+        return $response;
+    }
+}