fix(providers): handle python-build-standalone on Windows

The python-build-standalone archives extract with a python/ subdirectory
on all platforms, including Windows. Previously, the code assumed Windows
would use the embeddable package format (files in root), causing the shim
to fail to find the Python executable after installation.

This change removes the Windows-specific case in determineSourceDir() and
lets all platforms use the same logic: check for python/ subdirectory first,
then fall back to the extract root for older embeddable packages.

Author: CalvinAllen

src/runtimes/python/provider.go

@@ -91,18 +91,14 @@ func (p *Provider) downloadAndExtract(version, downloadURL, archiveName string)
 
 // determineSourceDir determines the source directory from extracted archive
 func determineSourceDir(extractDir string) string {
-	if goruntime.GOOS == constants.OSWindows {
-		// Windows embeddable: files are in extractDir root
-		return extractDir
-	}
-
-	// Unix python-build-standalone: files are in python/ subdirectory
+	// python-build-standalone: files are in python/ subdirectory (all platforms)
 	pythonSubdir := filepath.Join(extractDir, "python")
 	if _, err := os.Stat(pythonSubdir); err == nil {
 		return pythonSubdir
 	}
 
 	// Fallback: use extractDir if python/ doesn't exist
+	// (e.g., Windows embeddable packages from python.org have files in root)
 	return extractDir
 }
 
@@ -384,10 +380,10 @@ func (p *Provider) ExecutablePath(version string) (string, error) {
 	// Determine executable name and path based on platform
 	var pythonPath string
 	if goruntime.GOOS == constants.OSWindows {
-		// Windows embeddable package has python.exe in root
+		// Windows: python.exe is in the installation root
 		pythonPath = filepath.Join(installPath, "python.exe")
 	} else {
-		// Unix has python in bin/
+		// Unix: python is in bin/ subdirectory
 		pythonPath = filepath.Join(installPath, "bin", "python")
 	}