Bridges based on bridgev2 no longer expose a metrics endpoint, so the
playbook was publishing a Traefik route which could only ever yield an
HTTP 502.

Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/5487

Part of adopting a uniform naming policy for bridge variables,
where the variable prefix matches the role directory name.

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

Route the whole mautrix-signal HTTP port via Traefik under
`<matrix-fqn>/bridges/signal` and populate appservice.public_address,
reusing the matrix_bridges_exposure_* mechanism. The provisioning shared
secret is already auto-generated in group_vars, so the provisioning API
is enabled.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

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

Most of these files were defining a service, usually toward the end.
These lines have been moved upward.

Some components (mautrix-signal, mautrix-gmessages, etc.) were defining
a service conditionally (only if metrics are exposed, etc). This was
causing issues like these in the Traefik logs:

> level=error msg="service \"matrix-mautrix-twitter\" error: port is missing" providerName=docker container=matrix-mautrix-twitter-..

This moves the comments from being just in Jinja,
to actually ending up in the generated `labels` file,
which makes inspection of the final result easier.

Also, some new lines were added here and there to make labels
more legible.

The generated file may still include weird new-lines due to
various `if` statements yielding content or not, but that's not so ugly
anymore - now that we have proper start/end sections that are visible in
the final `labels` file.