Visiting the homeserver's root path used to redirect to Element Web,
but only when Element Web was the client the playbook installed. People
running Cinny, Commet, FluffyChat, Hydrogen, SchildiChat or Sable landed
on a bare homeserver page instead.

The wiring now builds matrix_playbook_public_client_urls — the public
URLs of every playbook-managed web client which is enabled, ordered by
preference — and redirects to the first of them. Element Web stays
first, so existing setups redirect exactly where they did before.

The URL is computed once and shared by all five homeserver
implementations, which each carried their own copy of the old
Element-Web-only expression. It honours each client's own scheme,
hostname and path prefix, so a client served under a subpath now gets
linked correctly.

Supersedes https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/5513

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