* feat: add inbound username support and USync username protocol
Aligns with Baileys upstream PR #2480. WhatsApp is rolling out an
inbound username field that maps to the user's LID. This change is
purely additive — it captures and propagates the new optional field
through types, decoders, USync queries, and group/contact events.
Skipped intentionally to preserve InfiniteAPI's LID/PN customization:
- handleGroupNotification in messages-recv.ts (custom LID->PN flow on
groups.upsert / participants.map). Username for these specific
events still flows via process-message's emitParticipantsUpdate
(reads message.key.participantUsername added in decode-wa-message).
Carousel/buttons code (messages.ts, messages-send.ts) untouched.
Co-Authored-By: Renato Alcara
Renato Alcara