fix(platform): support Windows storage and native filesystem boundaries

internal/backup/path_windows_test.go

@@ -0,0 +1,32 @@
+package backup
+
+import (
+	"archive/zip"
+	"context"
+	"errors"
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestRejectWindowsArchivePaths(t *testing.T) {
+	for _, name := range []string{"C:escape", "vault/note.md:stream", "vault/CON", "vault/dir./note.md"} {
+		t.Run(name, func(t *testing.T) {
+			file := filepath.Join(t.TempDir(), "invalid.zip")
+			f, err := os.Create(file)
+			if err != nil {
+				t.Fatal(err)
+			}
+			z := zip.NewWriter(f)
+			if _, err := z.Create(name); err != nil {
+				t.Fatal(err)
+			}
+			if err := errors.Join(z.Close(), f.Close()); err != nil {
+				t.Fatal(err)
+			}
+			if _, err := Extract(context.Background(), file, t.TempDir()); !errors.Is(err, ErrInvalidArchive) {
+				t.Fatalf("unsafe archive path accepted: %v", err)
+			}
+		})
+	}
+}