fix: open native directory picker for new instances

internal/platform/files/directory_picker_other.go

@@ -0,0 +1,18 @@
+//go:build !windows
+
+package files
+
+import (
+	"context"
+	"errors"
+)
+
+var ErrSelectionCanceled = context.Canceled
+
+type unsupportedDirectoryPicker struct{}
+
+func NewDirectoryPicker() DirectoryPicker { return unsupportedDirectoryPicker{} }
+
+func (unsupportedDirectoryPicker) ChooseDirectory(context.Context) (string, error) {
+	return "", errors.New("directory picker is only supported on Windows")
+}