Clear local and server messages

import { deleteAllMsgFromLocalAndSvr } from '@/uni_modules/unix-openim-sdk'

await deleteAllMsgFromLocalAndSvr()

This is a higher-risk account-wide local/server deletion. Explain scope and recovery behavior, require strong confirmation, and block concurrent mutations. Rebuild conversation and message state after success. On a timeout or ambiguous failure, query current state instead of assuming the operation was atomic.