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>

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

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

* add FluffyChat

* capitalization

* Update group_vars/matrix_servers

Co-authored-by: Slavi Pantaleev <slavi@devture.com>

* fix link in readme

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Co-authored-by: Slavi Pantaleev <slavi@devture.com>