nono.test.ts: the 'falls back when nono not on PATH' fixture links /usr/bin/echo, which macOS does not have #862

runCommandUnderNono() > warns and falls back when nono not on PATH (non-strict) in packages/cli/test/nono.test.ts builds a private PATH directory and symlinks /usr/bin/echo into it. macOS has no /usr/bin/echo (echo is /bin/echo), so the symlink dangles, the fallback command cannot run, and the test fails on every macOS host regardless of the code under test (seen on rockit with and without cli#850's change). The try { symlinkSync(...) } catch {} hides the cause.

What the fix does:

1. The fixture links the echo the host actually has (resolve it with command -v echo against the real PATH before replacing PATH, or use process.execPath with a tiny script instead of echo), and fails the test with a named message if no echo can be found instead of swallowing the error.
2. The test passes on macOS and Linux; CI's existing Linux lane keeps covering it.