[BUG]: Screensaver folder mode fallback loop / Missing UI input for directory path

[Leitner1]

Describe the bug

When configuring the screensaver mode to folder in the Admin Panel (Expert View enabled), there is no input field provided to specify the actual folder path. Instead, the UI only presents a file selection dropdown. Because a proper folder cannot be defined, the screensaver fails to load custom images and permanently falls back to displaying the default frames from resources/frames/.

Manual configuration overrides via my.config.inc.php are also ignored by the system.

Steps to reproduce the behavior

1. Go to the Admin Panel and ensure Expert View is enabled.
2. Navigate to the Screensaver configuration section.
3. Set the mode to folder.
4. Bug 1: Observe that there is no text input field for a folder path. Only a dropdown for single files is shown (which saves to image_source).
5. Save the configuration, click Open preview or wait for the screensaver timeout.
6. Bug 2: The screensaver starts but displays the fallback frames (resources/frames/) instead of custom images.

Expected behavior

When folder mode is selected, the UI should provide a text field to input a directory path (e.g., private/screensaver/). The screensaver should then iterate through all images inside that specified folder.

Photobooth Version

v4.99 Current Build

Browser and browser version

Chromium (Kiosk mode)

Operating System

Raspberry Pi OS 13.5 (trixie)

Additional context

Troubleshooting already performed
To rule out user error, the following steps were taken on the file system level, all without success:

• Manually edited /var/www/html/config/my.config.inc.php to bypass the broken UI. Tried injecting various keys (image_source, folder, folder_path, dir) pointing to a valid directory (private/screensaver/). The fallback loop persists.
• Verified Linux file permissions to rule out read errors: Executed sudo chown -R www-data:www-data and sudo chmod -R 755 on the private directory.
• Attempted to reverse-engineer the correct config variable by grepping the source code (lib/, template/, api/, config/) for "resources/frames", but the fallback seems to be dynamically generated or located elsewhere in this build.