Remove update_ini.sh and the env-var-to-ini pipeline. The container now
has two config modes:
- Simple: set MAIL_DOMAIN in .env, container generates chatmail.ini
with defaults via `cmdeploy init` on first start.
- Advanced: mount a custom chatmail.ini into the container; the init
step is skipped when the file already exists.
This eliminates the fragile FORCE_REINIT_INI_FILE / INI_CMD_ARGS
machinery and the env vars that duplicated chatmail.ini settings
Also add *.ini and .env to .dockerignore so local config files
don't leak into the image.
The Dockerfile will need access to chatmaild/ and cmdeploy/ source
trees to run CMDEPLOY_STAGES=install via pyinfra during image build,
moving install-time work out of container startup. The previous context
(./docker) only included helper scripts.
Also adds .dockerignore to exclude .git, data/, venv/ etc. from the
build context, and updates COPY paths accordingly.
