Fix package:
1. Newsletter form actions changed to /newsletter-subscribe.php so /el pages no longer 404.
2. newsletter-subscribe.php and newsletter-unsubscribe.php replaced with safer PHP versions.
3. send-contact.php replaced/added in root, /el, /en, /eng with safer PHP to avoid 500 error.
4. Contact forms now post to /send-contact.php.
5. Footer bottom black strip patched with CSS override, keeping terracotta footer tone.
6. Install app popup now: close 1-2 => may show again after about 1 minute on next eligible home visit, close 3 => pause 6 hours. Install click also pauses 6 hours.
