Pro Blanche Store Pro Max Client Bridge 6.2.4 Security Hardening

Added:
- Signed protected requests to the hub using the site token.
- Unique request IDs and timestamps for anti-replay protection.
- Extra browser security headers.
- Existing sync, license validation, last-good-bundle cache, product display, cart, checkout and API delivery behavior are preserved.

Compatibility:
- Use with PBS License Control Center 2.8.4 or newer.


== 6.2.5 Signature Fix ==
- Adds timestamp, request_id and request_signature to secured client requests when site_token is available.
- Fixes hub error: Secure request signature is missing. Update the client plugin.
- Keeps existing Hub Sync, debug shield, rate-limit backoff, and last-good-bundle behavior.
