fix(types): remove non-null assertions across 14 files

Files fixed:
- messages-recv.ts: 58 assertions → null guards, meId extraction, optional chaining
- process-message.ts: 38 assertions → remoteJid/participant guards, proto field checks
- chat-utils.ts: 31 assertions → proto field validation with Boom errors
- messages-send.ts: 20 assertions → meId extraction, participant guards
- chats.ts: 15 assertions → me guard, firstChild guard, jid guards
- messages.ts: 14 assertions → originalFilePath guard, key guards
- groups.ts: 12 assertions → attrs fallbacks with ??
- validate-connection.ts: 9 assertions → grouped proto field validation
- generics.ts: 1 assertion → versionLine guard
- history.ts: 2 assertions → key guards
- libsignal.ts: 1 assertion → deviceId guard
- sender-key-message.ts: 3 assertions → proto guards
- UsyncBotProfileProtocol.ts: 2 assertions → attrs guards
- example.ts: 3 assertions → optional chaining

https://claude.ai/code/session_01E2cfX1N3sJgCJBTvzGazSG

src/Socket/groups.ts

@@ -225,12 +225,12 @@ export const makeGroupsSocket = (config: SocketConfig) => {
 		groupAcceptInviteV4: ev.createBufferedFunction(
 			async (key: string | WAMessageKey, inviteMessage: proto.Message.IGroupInviteMessage) => {
 				key = typeof key === 'string' ? { remoteJid: key } : key
-				const results = await groupQuery(inviteMessage.groupJid!, 'set', [
+				const results = await groupQuery(inviteMessage.groupJid ?? '', 'set', [
 					{
 						tag: 'accept',
 						attrs: {
-							code: inviteMessage.inviteCode!,
-							expiration: inviteMessage.inviteExpiration!.toString(),
+							code: inviteMessage.inviteCode ?? '',
+							expiration: String(inviteMessage.inviteExpiration ?? ''),
 							admin: key.remoteJid!
 						}
 					}