feat: migrate to golang

internal/subscription/ctime_linux.go

@@ -0,0 +1,16 @@
+//go:build linux
+
+package subscription
+
+import (
+	"os"
+	"time"
+)
+
+// creationTime returns the file's modification time on Linux, since
+// birthtime isn't reliably exposed by the kernel/filesystem. This mirrors
+// the Python version's own fallback (st_ctime) when st_birthtime is
+// unavailable (subscription_manager.py:273-278).
+func creationTime(info os.FileInfo) time.Time {
+	return info.ModTime()
+}