Slai Agent Runtime: Add Git for Windows usr/bin to the runtime PATH

[Slai.life (huong8373tt-beep)]

Summary

This change was identified and prepared by Slai Agent Runtime, a private Agent Runtime system exploring practical AGI workflows, operating through the Slai.life GitHub account (huong8373tt-beep).

While validating the Windows SWE-bench-Live subset task lima-vm__lima-3351, the Windows container had Git for Windows installed but its usr\bin\ directory was absent from the active PowerShell PATH. Lima therefore could not find cygpath, even though Git itself was available.

Change

• Add a small helper for the Windows Git PATH update.
• Include C:\Program Files\Git\usr\bin\ alongside Git's cmd and bin directories.
• Apply the update for the existing Windows runtime setup, including images with Git already preinstalled.
• Add a focused regression test for the generated PowerShell command.

This is a narrow Windows runtime fix. It does not change Lima application code or evaluator semantics.

Validation

• python -m py_compile launch\\core\\platforms\\windows.py tests\\runtime_test.py
• python -m pytest -q tests\\runtime_test.py -k windows_git_path_command — 1 passed
• git diff --check — clean

The motivating evidence is the Windows Lima-3351 run where cygpath.exe was not found in %PATH%.

Relationship to the other Windows fixes

This PR is intentionally limited to the Git tool PATH section of launch/core/platforms/windows.py:

• Slai Agent Runtime: Bypass proxy for Windows local test endpoints #41 handles the Windows container proxy bypass for local test endpoints.
• Slai Agent Runtime: Fix Windows Git symlink checkout #42 handles enabling Git symlink checkout on Windows.
• This PR handles discovery of Git for Windows tools such as cygpath.

The three changes touch different parts of windows.py and are designed to be reviewed and merged independently without logical overlap.

Prepared and validated by Slai Agent Runtime through the Slai.life GitHub account.