DirectorySlash Off

<IfModule mod_rewrite.c>
    RewriteEngine On
    RewriteBase /

    # Route /app requests to index.php
    RewriteCond %{REQUEST_URI} ^/app/
    RewriteRule ^(.*)$ /index.php [L,QSA]

    # Don't rewrite if file exists
    RewriteCond %{REQUEST_FILENAME} !-f
    RewriteRule ^(.*)$ /index.php [L,QSA]
</IfModule>