The metrics endpoint was the only thing this bridge ever routed through
Traefik. With it gone, the container was still labeled `traefik.enable=true`
without defining any router, which makes Traefik fall back to its default
rule and produce a router pointing at nothing. It was also joining the
reverse-proxy network for no reason.

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

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>

Add the matrix-rustpush-bridge role, a Matrix <-> iMessage bridge built
on the mautrix-go bridgev2 framework using RustPush (OpenBubbles backend).

Unlike the existing mautrix-imessage/wsproxy bridge, it talks directly to
Apple's push notification service, so it needs neither a running Mac nor a
wsproxy on the homeserver. Each user supplies a hardware key extracted from a
Mac through the bridge bot's login flow.

The bridge uses its own bot username and puppet namespace (rustpushbot,
rustpush_*) so it does not collide with the wsproxy iMessage bridge.

This bridge is in early development and may have stability issues.