fix(terminal): check system Git paths before shutil.which on Windows (#47837)

[kyssta-exe]

Fixes #47837.

On Native Windows with both Git for Windows and WSL installed, _find_bash() resolves to WSL's bash.exe instead of Git for Windows' bash.exe. This is because shutil.which("bash") on the system PATH returns WSL's bash.exe (C:\Windows\system32\bash.exe), which is checked before the Git-for-Windows paths.

The fix reorders the lookup: system Git-for-Windows paths (Program Files\Git\bin\bash.exe, etc.) are now checked before falling back to shutil.which("bash"). This ensures Git Bash (MSYS) is preferred over WSL bash when both are available.

[alt-glitch]

Duplicate of #46586 — identical fix: moves the shutil.which("bash") fallback to after the Git-for-Windows path loop in tools/environments/local.py _find_bash(), so Git Bash is preferred over WSL's bash.exe. #46586 (2026-06-15) is the earlier open twin with the same mechanism.

Related: #47854 (same fix, later), #35675 (different mechanism — WSL cwd handling in base.py), and the source issue #47837.

[teknium1]

Superseded by PR #56384. This is the same _find_bash() reorder (Git for Windows before shutil.which), which was salvaged from the earliest submission of that fix (#46586) with authorship preserved. Correct fix — thanks for confirming the approach and referencing #47837.
#56384