Unify the two file picker screens / toggling .dotfile visibility

### ⚠️ 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

_Unsure whether this should be a bug report or feature request. Given it's not a glitch and a workaround exists, I went with feature request_

**TL;DR:** No quick and easy way to move into hidden .dotfiles/folders in the _dialog_ file-picker. I'd suggest updating the _dialog_ file-picker (settings → any setting which requires a file/path) to match functionality of the _full screen_ file-picker (main Notebook/Files tab)

**Description:** In general, I want .dotfiles (and .dotfolders) hidden. But occasionally I want to jump into a .dotfolder just one time.

**Example:** I accidentally changed the snippet folder path, and then couldn't* change it back to the original `.../markor/.app/snippets`
_(* Note: I did eventually find a workaround - see **Workaround** section below)_

**Explaination/Troubleshooting:** I've realised there are two file-pickers in Markor
* The full screen picker (i.e. the `Files` tab, of the "`Files` `ToDo` `QuickNote` `More`" main screen tabs)
- Search has options (e.g. regex)
- When .dotfiles are hidden, I can still search for e.g. `.app` and it will come up as a result. Perfect - a one-time way to move into a hidden folder.
- Sort options available, including ability to toggle .dotfiles visibility
* The dialog overlay (e.g. Settings → Other → Snippet / Template directory)
- Basic search only (no options/check boxes)
- Search doesn't bring up .dotfiles/folder results (except maybe when using the Workaround below - not tested)
- No sort options → can't toggle .dotfiles visibility here

**Workaround:** To fix my snippet setting described in "Example" section above, here's what I did:
* Go to the main screen Notebook/Files tab → Sort icon
- Tick (check) ".dotfiles"
* Go to Settings → Other → Snippet / Template directory
- `.../markor/.app/` folder is now visible (sort option affected this dialog too)
- Select/create `.../markor/.app/snippets`
* Go back to the main screen Notebook/Files tab → Sort icon
- Untick (uncheck) ".dotfiles" to return to normal behaviour

It's a pain of a process, and not something many users would think to try.

### Information

Android version: Android 16 (with Android security update 5-Feb-2026 & Google Play system update 1-Nov-2025)
ROM info: Stock ROM as shipped, not rooted, but Shizuku installed
Device: Pixel 9 Pro
App Version: 2.15.2

### Source

GitHub Releases

### Format / File type

Not specific

### Additional info / Log

```shell
-
```

Start by comparing the full-screen Files tab picker with the dialog overlay used by Settings → Other → Snippet / Template directory. Trace how search, sorting, and dotfile visibility are provided in each entry point. Done means the dialog picker offers the same practical way to reveal and enter hidden files or folders without changing the full-screen picker settings.

Written by the indexing model from the issue text.