Stacked on #2269 (back-nav scaffolding) plus the Telegram and Slack
PRs. They share the same scaffolding file from #2269 — they don't
compile without it, so they have to stack.
Both Teams paths already had a brightSelect at the right place, so we
just extend each with a Back option — no new prompts:
- Existing-credentials path: Yes/No confirm becomes Yes/No/Back
- Fresh-setup path: the very first stepGate ("How did that go?") gets
a 4th option. Subsequent stepGates keep the original 3 options so
we never lose mid-flow state.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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