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: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/Types/Contact.ts

@@ -9,6 +9,8 @@ export interface Contact {
 	name?: string
 	/** name of the contact, the contact has set on their own on WA */
 	notify?: string
+	/** username associated with this contact, when provided by WA */
+	username?: string
 	/** I have no idea */
 	verifiedName?: string
 	// Baileys Added

src/Types/Events.ts

@@ -81,6 +81,7 @@ export type BaileysEventMap = {
 		id: string
 		author: string
 		authorPn?: string
+		authorUsername?: string
 		participants: GroupParticipant[]
 		action: ParticipantAction
 	}
@@ -88,6 +89,7 @@ export type BaileysEventMap = {
 		id: string
 		author: string
 		authorPn?: string
+		authorUsername?: string
 		participant: string
 		participantPn?: string
 		action: RequestJoinAction

src/Types/GroupMetadata.ts

@@ -20,17 +20,20 @@ export interface GroupMetadata {
 	addressingMode?: WAMessageAddressingMode
 	owner: string | undefined
 	ownerPn?: string | undefined
+	ownerUsername?: string | undefined
 	owner_country_code?: string | undefined
 	subject: string
 	/** group subject owner */
 	subjectOwner?: string
 	subjectOwnerPn?: string
+	subjectOwnerUsername?: string
 	/** group subject modification date */
 	subjectTime?: number
 	creation?: number
 	desc?: string
 	descOwner?: string
 	descOwnerPn?: string
+	descOwnerUsername?: string
 	descId?: string
 	descTime?: number
 	/** if this group is part of a community, it returns the jid of the community to which it belongs */
@@ -56,6 +59,7 @@ export interface GroupMetadata {
 	/** the person who added you to group or changed some setting in group */
 	author?: string
 	authorPn?: string
+	authorUsername?: string
 }
 
 export interface WAGroupCreateResponse {

src/Types/Message.ts

@@ -19,7 +19,9 @@ export type WAContactMessage = proto.Message.IContactMessage
 export type WAContactsArrayMessage = proto.Message.IContactsArrayMessage
 export type WAMessageKey = proto.IMessageKey & {
 	remoteJidAlt?: string
+	remoteJidUsername?: string
 	participantAlt?: string
+	participantUsername?: string
 	server_id?: string
 	addressingMode?: string
 	isViewOnce?: boolean // TODO: remove out of the message key, place in WebMessageInfo