Replace hardcoded restart_necessary: true with computed values for:
conduit, continuwuity, dendrite, element-call, media-repo,
appservice-kakaotalk, and wechat.

Each role now registers results from config, support files, systemd service,
and docker image pull tasks, then computes a restart_necessary variable
from their combined .changed state. group_vars/matrix_servers is updated
to reference these variables instead of hardcoding true.

For dendrite, the systemd service template was also separated out of the
combined support-files with_items loop so it can be independently tracked.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>