RetroArch Android not detecting shaders outside shaders directory

Is there an existing issue for this?

• This is a bug in RetroArch frontend
• I have searched the existing issues

Description

shaders outside the shaders directory isn't being detected by RetroArch. it's been that way since 1.20 probably even before 1.20 as well. can't tell if this is intended so i created an issue.

https://github.com/user-attachments/assets/fbf00883-f451-49cb-87f6-3b2934f06209

Expected behavior

shaders outside the shaders directory should be detected as well.

Steps to reproduce the bug

1. download shaders somewhere. (make sure that it's for whatever video driver that you're using.)
2. put/extract it on a folder where it's easy to find. (e.g. RetroArch folder)
3. open RetroArch and boot a game.
4. go to quick menu and scroll down to shaders.
5. go to load preset then navigate to where you put the shaders that you downloaded.

Version/Commit

1.21.0 (d40625b)

Bisect Results

no, it didn't work on older versions.

Present in the nightly version

Yes, this is reproduced in the nightly build

Platform & operating system

Android 12

Affected Cores

any.

Environment information

No response

Relevant log output

Reproduce the issue on Android 12 using RetroArch 1.21.0 or the nightly build, following the listed steps with a shader preset outside the shaders directory. Trace the Quick Menu shader preset loading and directory navigation behavior; done means externally placed shaders can be located and loaded.