v4.5.0 - Payment Sent state, instant verification, intent settlement reporting

Added

• "Payment Sent" state on the thank-you page. With REAL8 Wallet v4.7.10+, the wallet appends the Stellar tx hash to the return URL; the thank-you page then shows "Payment Sent, confirming on the Stellar network" instead of the pay-now instructions. English and Spanish.
• Immediate verification on arrival. Forced Horizon check ~1 s after landing with a tx hash, then 8 s polling. Confirmation typically lands in seconds instead of up to a minute.
• Settlement reported to the payment-intent API (POST /payment-intents/{id}/paid, HMAC, requires api.real8.org v1.7.6+), so revisited pay links show "paid".

Fixed

• Manual-check feedback messages no longer fire for automatic background checks.