fix(types): resolve all TypeScript compilation errors from non-null assertion removal

Fixes:
- chats.ts: revert encodeResult/initial to ! (guaranteed by callback assignment)
- groups.ts: fix operator precedence with ?? (wrap +attrs in parens), fix groupId type
- messages-recv.ts: extract messageKey.id to local const with fallback
- socket.ts: revert onClose! (guaranteed by synchronous callback assignment)
- event-buffer.ts: add 'notify' fallback for MessageUpsertType
- messages.ts: add filePath const after null guard, fix contextInfo type assertion
- noise-handler.ts: restore array index ! (guaranteed by length check)

Build now compiles with zero new errors.

https://claude.ai/code/session_01E2cfX1N3sJgCJBTvzGazSG

src/Socket/messages-recv.ts

@@ -156,16 +156,17 @@ export const makeMessagesRecvSocket = (config: SocketConfig) => {
 			throw new Boom('Not authenticated')
 		}
 
-		if (await placeholderResendCache.get(messageKey?.id)) {
+		const msgId = messageKey?.id ?? ''
+		if (await placeholderResendCache.get(msgId)) {
 			logger.debug({ messageKey }, 'already requested resend')
 			return
 		} else {
-			await placeholderResendCache.set(messageKey?.id, true)
+			await placeholderResendCache.set(msgId, true)
 		}
 
 		await delay(2000)
 
-		if (!(await placeholderResendCache.get(messageKey?.id))) {
+		if (!(await placeholderResendCache.get(msgId))) {
 			logger.debug({ messageKey }, 'message received while resend requested')
 			return 'RESOLVED'
 		}
@@ -180,9 +181,9 @@ export const makeMessagesRecvSocket = (config: SocketConfig) => {
 		}
 
 		setTimeout(async () => {
-			if (await placeholderResendCache.get(messageKey?.id)) {
+			if (await placeholderResendCache.get(msgId)) {
 				logger.debug({ messageKey }, 'PDO message without response after 8 seconds. Phone possibly offline')
-				await placeholderResendCache.del(messageKey?.id)
+				await placeholderResendCache.del(msgId)
 			}
 		}, 8_000)