fix(executor): implement Windows disk stat in getDiskMB using GetDiskFreeSpaceEx

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: 2 people

src/code.cloudfoundry.org/executor/depot/depot_windows.go

@@ -3,6 +3,19 @@
 
 package depot
 
-func getDiskMB(_ string, fallback int) int {
-	return fallback
+import "golang.org/x/sys/windows"
+
+func getDiskMB(diskPath string, fallback int) int {
+	if diskPath == "" {
+		return fallback
+	}
+	pathPtr, err := windows.UTF16PtrFromString(diskPath)
+	if err != nil {
+		return fallback
+	}
+	var freeBytesAvailable, totalBytes, totalFreeBytes uint64
+	if err := windows.GetDiskFreeSpaceEx(pathPtr, &freeBytesAvailable, &totalBytes, &totalFreeBytes); err != nil {
+		return fallback
+	}
+	return int(freeBytesAvailable / (1024 * 1024))
 }