Add conditional restart support to service roles

Track config/image/systemd changes via register: directives and compute
a _restart_necessary variable for each service role, allowing the
systemd_service_manager to skip unnecessary restarts during install-* runs.

Covers 22 service roles: alertmanager-receiver, appservice-draupnir-for-all,
bridge-mautrix-wsproxy (+ syncproxy), cactus-comments, cactus-comments-client,
corporal, element-admin, ldap-registration-proxy, livekit-jwt-service, matrixto,
pantalaimon, prometheus-nginxlog-exporter, rageshake, registration, static-files,
sygnal, synapse-admin, synapse-auto-compressor, synapse-reverse-proxy-companion,
synapse-usage-exporter, and user-verification-service.

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

roles/custom/matrix-matrixto/defaults/main.yml

@@ -170,3 +170,13 @@ matrix_matrixto_systemd_wanted_services_list_custom: []
 
 # Additional environment variables.
 matrix_matrixto_environment_variables_additional_variables: ""
+
+# matrix_matrixto_restart_necessary controls whether the service
+# will be restarted (when true) or merely started (when false) by the
+# systemd service manager role (when conditional restart is enabled).
+#
+# This value is automatically computed during installation based on whether
+# any configuration files, the systemd service file, or the container image changed.
+# The default of `false` means "no restart needed" — appropriate when the role's
+# installation tasks haven't run (e.g., due to --tags skipping them).
+matrix_matrixto_restart_necessary: false

roles/custom/matrix-matrixto/tasks/install.yml

@@ -24,6 +24,7 @@
   with_items:
     - env
     - labels
+  register: matrix_matrixto_support_files_result
 
 - name: Ensure Matrix.to repository is present on self-build
   ansible.builtin.git:
@@ -70,3 +71,12 @@
     src: "{{ role_path }}/templates/systemd/matrix-matrixto.service.j2"
     dest: "{{ devture_systemd_docker_base_systemd_path }}/{{ matrix_matrixto_identifier }}.service"
     mode: "0644"
+  register: matrix_matrixto_systemd_service_result
+
+- name: Determine whether Matrix.to needs a restart
+  ansible.builtin.set_fact:
+    matrix_matrixto_restart_necessary: >-
+      {{
+        matrix_matrixto_support_files_result.changed | default(false)
+        or matrix_matrixto_systemd_service_result.changed | default(false)
+      }}