feat(i18n-ko): CLI — human help and TUI chrome

## Problem

CLI human help and TUI chrome are effectively `en`-only in `ko`. Machine-readable output must stay locale-independent, but human-facing help / pickers / status lines should follow the `ko` preference.

## Desired outcome

Add `ko` catalog for human-facing CLI/TUI, following #2672 explicit policy:

- Human help: `packages/cli/src/cli-ui-locale.ts`, `onboarding-catalog.ts`, `tui-primary-guidance`, `tui-session-status`, `pi-tui-*` pickers/status
- Locale selection: explicit `override` + system/environment fallback via same `resolveSystemUiLocale` logic
- Machine output / protocol / JSONL / exit semantics unchanged and locale-independent

## Alternatives or workarounds

Keep CLI/TUI in English for `ko`.

## Acceptance criteria

- [ ] `ko` selected → human help / TUI chrome renders Korean; `en` unchanged
- [ ] `--locale ko` override works; `auto` follows system `ko-KR`
- [ ] Machine-readable / JSONL output unchanged
- [ ] CLI locale-focused suites green

Parent: #3974