feat: honor NO_COLOR and keep pipe output parseable

We check TTY in a few places (`logo.ts` already honors `NO_COLOR`; `docs ask` disables the spinner off-TTY) but human tables always use Unicode box drawing (`src/output.ts` + cli-table3), and `elastic status` prints checkmarks. No `--no-color`. Piped human output is not a stable TSV.

Pre-1.0, do not add a pager. Do:

- Honor `NO_COLOR` and `FORCE_COLOR` everywhere we emit ANSI
- Add `--no-color` as a global alias for `NO_COLOR`
- When stdout is not a TTY and `--json` is absent, render tables as TSV (or fall back to JSON). Unicode borders and checkmarks are TTY-only
- Keep stdout = data, stderr = diagnostics (audit `docs` / `status` / extensions)

Relates to #623 (nested object rendering). This issue is the output contract, not that CAT bug.

Acceptance: `NO_COLOR=1 elastic status` has no ANSI and no checkmark glyphs. `elastic stack es cat indices | cat` is TSV or JSON, not a box table. Tests cover TTY and non-TTY.

Start with src/output.ts, logo.ts, and the docs, status, and extensions output paths; inspect the existing cli-table3 and TTY handling. Trace where ANSI, Unicode borders, checkmarks, and stdout diagnostics are emitted, then add TTY and non-TTY tests. Done means NO_COLOR and --no-color suppress ANSI, piped human output is TSV or JSON, and stdout contains data only.

Written by the indexing model from the issue text.