Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

For each of the 34 roles (3 clients, 9 bots, 22 bridges), this commit:
- Adds `_restart_necessary: false` default variable
- Adds `register:` directives to config/image/systemd tasks
- Computes `_restart_necessary` via set_fact (OR of all .changed results)
- Wires `(_restart_necessary | bool)` in group_vars/matrix_servers

This allows the systemd service manager to skip unnecessary restarts
when running install-* tags and nothing actually changed.

Service roles and complex multi-service roles will follow separately.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

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

This:

- brings consistency - no more mixing `_name_prefix` and `_registry_prefix`
- adds extensibility - a future patch will allow reconfiguring all registry prefixes for all roles in the playbook

We still have `_docker_` vs `_container_` inconsistencies.
These may be worked on later.

This is done for a few reasons:

- less globals and more indepdendence for each role is better. We rely
  on various externally-hosted roles and they don't rely on this global
  either.

- `matrix_container_global_registry_prefix` could make people think they
  could just override this variable and have all their images pull from
  elsewhere. This is rarely the case, unless you've taken special care
  to mirror all the various components (from their respective
  registries) to your own. In such a case, you probably know what you're
  mirroring and can adjust individual variables.

- nowadays, various components live on different registries.
  With Docker Inc tightening rate limits for Docker Hub, it's even more
  likely that we'll see increased diversity in where images are hosted

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

* Update matrixdotorg/mjolnir Docker tag to v1.8.1

* Upgrade Mjolnir to v1.8.3

---------

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>
Co-authored-by: Slavi Pantaleev <slavi@devture.com>

Related to 0241c71a4c

Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/3270#issuecomment-2143782962

With this change, it should be possible for people to adjust the Docker
dependency from `docker.service` to something else (e.g. `pkg-ContainerManager-dockerd.service`),
or to completely eliminate it by setting `devture_systemd_docker_base_docker_service_name` to an empty string.

This makes it easier for people to use the playbook against a Synology DSM server.

Please note that This Mjolnir version bump technnically is missing some extra stuff that mjolnir claims we should do but it didnt work when i tried it and well my mjolnir deployment has been running this since release day almost and its fine. No errors in log that are unexpected. (Mjolnir throws errors in the log for anyone who wonders for various things that are fine. Like if a protection is off that is an error. Its due to how matrix-bot-lib works.)

This paves the way for installing other roles into `roles/galaxy` using `ansible-galaxy`,
similar to how it's done in:

- https://github.com/spantaleev/gitea-docker-ansible-deploy
- https://github.com/spantaleev/nextcloud-docker-ansible-deploy

In the near future, we'll be removing a lot of the shared role code from here
and using upstream roles for it. Some of the core `matrix-*` roles have
already been extracted out into other reusable roles:

- https://github.com/devture/com.devture.ansible.role.postgres
- https://github.com/devture/com.devture.ansible.role.systemd_docker_base
- https://github.com/devture/com.devture.ansible.role.timesync
- https://github.com/devture/com.devture.ansible.role.vars_preserver
- https://github.com/devture/com.devture.ansible.role.playbook_runtime_messages
- https://github.com/devture/com.devture.ansible.role.playbook_help

We just need to migrate to those.