Raff v0.7.1: Stripe, Google Pay / Apple Pay, and dual payment modes

Added

Stripe payment flow with comprehensive validation and real-time webhook status updates.

Google Pay and Apple Pay support.

Dual payment modes. Automatic 3DS detection decides per card between manual payment and automatic end-of-period charging.

Welcome credit increased to $200, valid for 2 months.

Fixed

Billing calculation problems on the UI side and numerous payment validation bugs.