Implements three UX improvements (TODO #1–#3):
- Back navigation: Esc returns to the previous input step. The Model keeps
a history stack of input steps (advance/goBack helpers); action/wait
steps are excluded via isInputStep so back never re-enters a
side-effecting step. Form values are preserved.
- Review step (StepReview): shows all collected config for confirmation
before any file is written; Enter installs, Esc edits.
- Retry vs. fix: transient failures (image pull, container run) offer
"r: tentar novamente" instead of quitting; validation failures route
back to the relevant form to correct the value.
Adds nav_test.go for the history/navigation logic and updates
README/CLAUDE/docs (incl. docs/TODO.md tracking the remaining ideas).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
