Replaces `community.docker.docker_image` with the modern
`docker_image_pull` module. Drops the `ansible_version` compatibility
ladder and the now-redundant `_container_image_force_pull` variable
(the new pull module handles registry refresh natively via `pull: always`).

Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/5191.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/4776

Supersedes https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/4777

This commit adds copyright attributions in SPDX to the files for matrix-cactus-comments and matrix-cactus-comments-client, following REUSE's specification.

Signed-off-by: Suguru Hirahara <acioustick@noreply.codeberg.org>

This is split out from matrix-cactus-comments (see 241779b583),
but also heavily inspired by `matrix-static-files`.