On Windows (OSTYPE msys/cygwin) gstack-doctor adds a 'windows bash' row from
lib/script-invocation.ts resolveWindowsBash, run through the new thin
bin/gstack-windows-bash.ts with the bun on PATH: the resolved bash and the
override or discovery step that chose it, a warn when GSTACK_GIT_BASH and
GSTACK_BASH differ, and a fail carrying the BASH_UNAVAILABLE line (every
candidate with its rejection reason) when none qualifies. Tests inject the
platform (GSTACK_DOCTOR_PLATFORM) and the discovery inputs
(GSTACK_DOCTOR_BASH_PROBE) so the row runs on every OS.
Co-authored-by: capy-ai[bot] <230910855+capy-ai[bot]@users.noreply.github.com>
