fix(types): add CreateMediaBuySubmittedResponse alias and fix handler return type#573

bokelley wants to merge 2 commits intomainadcontextprotocol/adcp-client-python:mainfrom

claude/issue-570-create-media-buy-submitted-aliasadcontextprotocol/adcp-client-python:claude/issue-570-create-media-buy-submitted-aliasCopy head branch name to clipboard