Fix lint and failing tests

proxy/internal/flock/flock_other.go

@@ -11,7 +11,7 @@ import (
 // that no lock was acquired; callers must treat a nil file as "proceed
 // without lock" rather than "lock held by someone else."
 func Lock(_ context.Context, _ string) (*os.File, error) {
-	return nil, nil
+	return nil, nil //nolint:nilnil // intentional: nil file signals locking unsupported on this platform
 }
 
 // Unlock is a no-op on non-Unix platforms.