cli: --yes flag is inert (no prompts exist yet for it to suppress)

[dipto0321]

Describe the bug

--yes (internal/cli/upgrade.go:34,49, _ = yes // TODO: use for non-interactive mode) is fully inert — there is no interactive prompt anywhere in the current runUpgrade flow for it to suppress (no manager-selection prompt, no cleanup prompt exists yet), so nodeup upgrade is already fully non-interactive regardless of --yes. README's Quickstart lists --yes as if it changes behavior ("Non-interactive (CI-friendly)"), which is misleading today.

Note: the cleanup-step part of this finding (--no-cleanup and the "remove old versions" step described in README's "How it works" step 8) is already tracked in detail by #41, which specs out the full cleanup implementation including --cleanup/--cleanup-version flags. This issue is scoped down to just the --yes flag, since #41's design doesn't fully cover it (its --cleanup flag is a separate non-interactive toggle scoped to the cleanup step only, not a general "assume yes to everything" flag).

Suggested fix

Once #41 lands (adding the first real interactive prompt to nodeup upgrade), wire --yes to auto-confirm it and any other future prompts, or — if #41's --cleanup flag is judged sufficient on its own — remove --yes from the flag set and README until there's an actual prompt for it to control, to avoid advertising a no-op flag.

Severity

Low — no incorrect behavior, just an unimplemented/misleading flag.

[dipto0321]

Superseded: PR #56 (merged) implemented the cleanup feature, so --yes is no longer inert — it's now wired up, but buggy in a specific combination. Tracked precisely as #57 (--yes silently overrides --no-cleanup). Closing this one since its premise (the flag does nothing) is no longer true.