Photos uploaded from gallery are not stored in the configured subfolder

[IvaKuklica]

Description
When a user attaches a photo from the device gallery using the Attachment widget (configured with a subfolder path), the photo is not saved to the correct subfolder. Unlike the camera flow, the gallery flow silently places the photo outside the configured subfolder with no error or warning shown to the user.

Environment
[ ] Staging

Application (+ app version, build, operating system)
Mergin Maps Mobile App — Android

• App version: 2026.1.2 / / build 785451
• Device/OS: Samsung Galaxy A53 5G - Android 15 / build 785451

Steps to reproduce

1. In QGIS, create a project with a survey layer containing a photo field using the Attachment widget.
2. Set the Default path of the Attachment widget to a subfolder, e.g. @project_folder + '/Photos/'.
3. Set Store path as to Relative to project path.
4. Save and sync the project to the server via the Mergin Maps plugin.
5. On the Samsung Galaxy A53, open the Mergin Maps app and download the project.
6. Create a new feature and open the photo field.
7. Select Gallery (instead of Camera) and choose an existing photo from the device.
8. Save the feature and sync the project.
9. Check the project folder structure on the server or locally to verify where the photo was saved.

Actual results
The photo selected from the gallery is not stored in the configured subfolder (e.g. /Photos/). The photo is saved to an incorrect location with no error or warning displayed to the user.

Expected results
Photos uploaded from the gallery should be stored in the same configured subfolder path as photos taken with the camera (e.g. /Photos/), consistent with the Attachment widget's Default path setting.

[Withalion]

@IvaKuklica I was not able to consistently reproduce this issue on Android/Linux. If some error happened I got a notification about it.