Route the whole mautrix-bluesky HTTP port via Traefik under
`<matrix-fqn>/bridges/bluesky` and populate the existing
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>