Updated PHP version with shared header/footer and cookie consent

What was changed:
1. All top-level .html pages have been converted to .php.
2. Header code has been moved to: includes/header.php
3. Footer code has been moved to: includes/footer.php
4. Cookie consent popup has been added to every page through: includes/cookie-consent.php
5. Internal page links have been updated from .html to .php.

How to upload:
- Upload all files/folders from this package to your hosting public_html folder.
- Make sure the server supports PHP.
- Use index.php as the home page.
- If old .html files already exist on hosting, remove or redirect them to the new .php URLs.

Important:
- The cookie popup privacy policy link currently points to privacy-policy.php.
- If you do not have a privacy policy page yet, create privacy-policy.php or change the link inside includes/cookie-consent.php.
- If Google Analytics, Meta Pixel, Google Ads, or any marketing scripts are already placed directly in the <head>, move them inside the loadAnalyticsScripts() or loadMarketingScripts() functions in includes/cookie-consent.php for proper consent-based loading.
