Separate completed tool actions from narration formatting failures

A successful provider response and completed result card can coexist with a later host narration formatting error. Treat these as separate stages: never retry a completed write merely to repair narration. A sandboxed card iframe can provide its own visible overflow rail and brief-summary routing guidance, but cannot style the parent conversation scroller. Preserve exact shared-link query bytes and test clipboard denial with a manual-selection fallback instead of claiming a copy succeeded.