External Apps download data directly to the docker image, not host storage (Docker on Unraid)

Describe the bug

I originally posted this to docker-socket-proxy, but think app_api might be the more appropriate repo?
https://github.com/nextcloud/docker-socket-proxy/issues/40

Docker image size limit is exceeded during external app installation, causing install to fail.

Steps/Code to Reproduce

1. Configure and test the Daemon
2. Run the test deployment
3. Install an external App (STT Whisper 2)
4. Data for both the test deployment as well as the installed app is saved to the docker image /volumes dir. As the STT Whisper app has a significant amount of AI model data, the docker image size limit is exceeded causing the install to fail.

Expected Results

I am not a dev, so this could be a misunderstanding on my part, but I thought the docker image held executable binaries, whereas application data (such as AI models in this specific case) should be stored elsewhere on the host storage.

Assuming I'm not wrong, there should be a host path env variable for downloaded data to be saved to the host storage outside the docker image (since my nextcloud instance is installed via docker as well, presumably this path can be read/imported from the main nextcloud installation).

If this already exists, could the docs be updated to include the container path where downloaded external app data will be saved so that we can map it appropriately on the host system?

Actual Results

Docker image size limit exceeded, causing exapp install to fail.

Setup configuration

Web server: Nginx

Database: Maria 10.11

PHP version: 8.3

Nextcloud version: 29.0.4

Operating system: Docker / Unraid 6.12.13

Start with the Daemon configuration and test deployment described in the reproduction steps, then trace where external-app data, including STT Whisper 2 models, is written inside the container. Check whether host-storage mapping is already supported and identify the relevant container path. Done means external-app installation no longer exhausts the Docker image and the storage mapping is documented.