fix(swarm): gate the post-deploy converge wait on the effective role mode

cdf544c35 switched the gate to compose_mode, but post_deploy.yml runs in
roleless include_tasks contexts where the sys-svc-compose defaults are
not in scope, so every compose deploy died with 'compose_mode is
undefined'. Use the compose_mode_force-or-DEPLOYMENT_MODE resolution the
lookup plugins and deploy.yml.j2 already apply.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

roles/sys-svc-compose/tasks/utils/post_deploy.yml

@@ -22,4 +22,4 @@
   delay: 2
   changed_when: false
   until: _swarm_tasks_ready is succeeded
-  when: compose_mode == 'swarm'
+  when: (compose_mode_force | default('') or DEPLOYMENT_MODE) == 'swarm'