v1.8.0 - composer push prompt and accounts

feat: in-conversation push prompt, multi-account, and pre-push scrub

A composer button fills a push prompt into the current input via
inputActions.setDraft (never auto-sends). Accounts are managed by name only:
no tokens are stored, authentication stays in Git Credential Manager and
switching just changes the default identity. A scrub route scans the files a
push would publish for the personal account, tokens, keys and emails; the
repository itself has been cleaned so the published content carries the
project identity rather than a personal handle.