feat: add inbound username support and USync username protocol (#382)

* 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

src/WAUSync/Protocols/USyncContactProtocol.ts

@@ -13,11 +13,37 @@ export class USyncContactProtocol implements USyncQueryProtocol {
 	}
 
 	getUserElement(user: USyncUser): BinaryNode {
-		//TODO: Implement type / username fields (not yet supported)
+		if (user.phone) {
+			return {
+				tag: 'contact',
+				attrs: {},
+				content: user.phone
+			}
+		}
+
+		if (user.username) {
+			return {
+				tag: 'contact',
+				attrs: {
+					username: user.username,
+					...(user.usernameKey ? { pin: user.usernameKey } : {}),
+					...(user.lid ? { lid: user.lid } : {})
+				}
+			}
+		}
+
+		if (user.type) {
+			return {
+				tag: 'contact',
+				attrs: {
+					type: user.type
+				}
+			}
+		}
+
 		return {
 			tag: 'contact',
-			attrs: {},
-			content: user.phone
+			attrs: {}
 		}
 	}