Package: verify + index (single-download) for protected automatic download
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Files included:
- verify.php   -> the verification landing page (use as the site's entry point).
- index.php    -> the download page; reads links.txt (first non-empty line) and starts download exactly once using a hidden iframe.
- links.txt    -> put your download URL on the first non-empty line (no extra text).
- README.txt   -> this file with instructions.

Usage:
1. Register your site for Google reCAPTCHA v2 (checkbox) at https://www.google.com/recaptcha/admin and get keys.
2. Edit verify.php and replace placeholders with your keys.
3. Upload all files to the same folder on your hosting (e.g., public_html).
4. Make verify.php the page visitors hit first (set as index or redirect root to it).
5. Put your download URL in links.txt (first non-empty line).
6. After successful verification, verify.php redirects to index.php, which triggers the download once.

Notes:
- This version uses only a hidden iframe to prevent duplicate downloads.
- Some browsers may still block downloads from cross-origin iframes. If so, host the file on the same domain or ensure the remote server sends Content-Disposition: attachment.
- Keep your reCAPTCHA secret key private.
