docker: widen build context to repo root for build-time install stage

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.

.dockerignore

@@ -0,0 +1,7 @@
+.git
+data/
+venv/
+__pycache__
+*.pyc
+*.orig
+.pytest_cache

docker-compose.yaml

@@ -1,8 +1,8 @@
 services:
   chatmail:
     build:
-      context: ./docker
-      dockerfile: chatmail_relay.dockerfile
+      context: ./
+      dockerfile: docker/chatmail_relay.dockerfile
       tags:
         - chatmail-relay:latest
     image: chatmail-relay:latest

docker/chatmail_relay.dockerfile

@@ -55,12 +55,12 @@ RUN apt-get update && \
 WORKDIR /opt/chatmail
 
 ARG SETUP_CHATMAIL_SERVICE_PATH=/lib/systemd/system/setup_chatmail.service
-COPY ./files/setup_chatmail.service "$SETUP_CHATMAIL_SERVICE_PATH"
+COPY ./docker/files/setup_chatmail.service "$SETUP_CHATMAIL_SERVICE_PATH"
 RUN ln -sf "$SETUP_CHATMAIL_SERVICE_PATH" "/etc/systemd/system/multi-user.target.wants/setup_chatmail.service"
 
-COPY --chmod=555 ./files/setup_chatmail_docker.sh /setup_chatmail_docker.sh
-COPY --chmod=555 ./files/update_ini.sh /update_ini.sh
-COPY --chmod=555 ./files/entrypoint.sh /entrypoint.sh
+COPY --chmod=555 ./docker/files/setup_chatmail_docker.sh /setup_chatmail_docker.sh
+COPY --chmod=555 ./docker/files/update_ini.sh /update_ini.sh
+COPY --chmod=555 ./docker/files/entrypoint.sh /entrypoint.sh
 
 ## TODO: add git clone.
 ## Problem: how correct save only required files inside container....