Touch parent folders when editing a file

### ⚠️ This issue respects the following points: ⚠️

- [X] This is a **enhancement/feature request**. Not a [bug or question](https://github.com/gsantner/markor/issues/new/choose).
- [X] The topic is **not** already reported at [Issues](https://github.com/gsantner/markor/issues?q=#js-issues-search). _(I've searched it)_.
- [X] Markor **is** up to date. See [Releases](https://github.com/gsantner/markor/tags) for the latest version. Updates are available from [F-Droid](https://f-droid.org/en/packages/net.gsantner.markor/) and GitHub.
- [X] The wanted feature/enhancement is not present in the latest development version (git master). (Please [download](https://nightly.link/gsantner/markor/workflows/build-android-project/master) and try the test version of Markor, named **Marder**. Don't worry; Markor and Marder appear as completely separate applications. You can install both side-by-side, and Markor's settings are not touched. If your desired feature is present, you don't need to open this issue. The change will be part of the next Markor update.)

### Description

1. Currently, when _sorting folders first_ option is turned off, when opening one of the folders and editing one of the notes inside:
2. The _file_ is touched (modification date is updated). But the _folder_ is **not touched**, its modification date remains in the past.
3. This is a problem because from the main menu, it is not possible to tell which folder was edited last.

### Information

Android version: 13
Device: Pixel a5
App Version: 2.12.5

### Source

GitHub Releases

### Format / File type

Not specific

### Additional info / Log

```shell
-
```

Start by reproducing the behavior on Android 13: edit a note inside a folder with “sorting folders first” disabled, then compare the file and parent-folder modification dates. Trace the file-editing flow and determine where the parent folder would need to be touched. Done means the edited folder’s date reflects the edit and the existing folder sorting behavior can show it as most recent.

Written by the indexing model from the issue text.