Fix CI Docker-in-Docker deployment, introduce vfs storage-driver, add inner dockerd bootstrap, enable portable json-file logging when running inside a container, and update workflow triggers for multi-branch testing.

Includes:
- Rewrite of test-deploy workflow to use isolated inner dockerd with privileged mode.
- Switch logging drivers to 'json-file' when IS_CONTAINER=true for compatibility with non-systemd CI runners.
- Adjust Dockerfile to install docker CLI and simplify package setup.
- Improve inventory creation and deploy steps for CI stability.
- Fully compatible with Ansible 2.20 variable handling.

Conversation reference:
https://chatgpt.com/share/6930e285-9604-800f-aad8-7a81c928548c

roles/web-app-nextcloud/templates/docker-compose.yml.j2

@@ -5,7 +5,7 @@
     image: "{{ NEXTCLOUD_PROXY_IMAGE }}:{{ NEXTCLOUD_PROXY_VERSION }}"
     container_name: "{{ NEXTCLOUD_PROXY_CONTAINER }}"
     logging:
-      driver: journald
+      driver: {{ "json-file" if IS_CONTAINER | bool else 'journald' }}
     restart: {{ DOCKER_RESTART_POLICY }}
     ports:
       - "127.0.0.1:{{ NEXTCLOUD_PORT }}:{{ container_port }}"
@@ -99,7 +99,7 @@
     image: "{{ NEXTCLOUD_IMAGE }}:{{ NEXTCLOUD_VERSION }}"
     restart: {{ DOCKER_RESTART_POLICY }}
     logging:
-      driver: journald
+      driver: {{ "json-file" if IS_CONTAINER | bool else 'journald' }}
     volumes:
       - data:{{ NEXTCLOUD_DOCKER_WORK_DIRECTORY }}
     entrypoint: /cron.sh