Fix Windows VBS launcher Python detection

[rpatel622]

What changed

• Replaced the fragile pyw.exe detection path with explicit support for the standard Windows py.exe launcher.
• Added Python 3.13, 3.12, and 3.11 discovery.
• Added fallback discovery for normal per-user and system-wide pythonw.exe installations.
• Added a clear error when the launcher is run from inside the ZIP or the bundle is incomplete.
• Added a clear Python installation message instead of silently doing nothing.

Root cause

The original VBS launcher checked only the executable portion of entries such as pyw.exe -3.11. pyw.exe is not consistently installed, while the standard Windows launcher is usually py.exe. The version arguments were also not included in the original availability check.

Validation needed

This should be tested on Windows with:

• python.org Python 3.11, 3.12, and 3.13 installations
• Python launcher enabled and disabled
• per-user and all-users installs
• paths containing spaces
• running from an extracted bundle and from inside a ZIP

The GitHub connector environment cannot execute Windows Script Host, so native Windows validation is still required.