<IfModule mod_rewrite.c>
  RewriteEngine On
  RewriteBase /app/

  # Redireciona todas as requisições para o index.html
  RewriteCond %{REQUEST_FILENAME} !-f
  RewriteCond %{REQUEST_FILENAME} !-d
  RewriteRule ^(.*)$ /app/index.html [L,QSA]
</IfModule>