Small Docker fixes & features

[joleaf]

Hi,
small improvements for the Dockerfile:

• Fix a permission error in the Dockerfile (the app container had no permission to create a folder/file in the upload folder and failed )
• Add healthcheck in the docker-compose.yml file to prevent the container app from failing, if the postgres container is not ready
• Add a docker-compose-dev.yml file (and the description to use it) to easily create a local test environment
• Renamed docker-compose ... -> docker compose ..(see https://docs.docker.com/compose/migrate/)

[alxlion]

Nice to have 👍 thanks !