Windows shell detection: single Git Bash path, missing cmd.exe and WSL

[johnkozaris]

Problem

detectWindows() in src/main/shell-detector.ts has three gaps:

1. Git Bash: Only checks C:\Program Files\Git\bin\bash.exe. Fails if Git is installed in Program Files (x86), %LOCALAPPDATA%\Programs\Git, or a custom location.
2. cmd.exe: Not detected at all — Command Prompt is always available on Windows but missing from the shell menu.
3. WSL: Not detected — wsl.exe is present on any Windows 10+ with WSL enabled.

Fix

• Check multiple Git Bash paths + where.exe bash fallback
• Add cmd.exe (always available)
• Detect C:\Windows\System32\wsl.exe

[johnkozaris]

Fixed in #31 — Windows: multiple Git Bash paths, cmd.exe, WSL, Nushell, PowerShell with versions.