fix: revert setup.yml, add livekit.yml standalone playbook

- Revert setup.yml to use galaxy/livekit_server (avoids loading all
  uninstalled galaxy roles when running with --tags)
- Add livekit.yml: minimal standalone playbook that only includes
  galaxy/systemd_docker_base and custom/livekit_server, so livekit
  setup can run independently without requiring all other galaxy roles

Usage:
  ansible-playbook -i inventory/hosts livekit.yml \
    --tags=setup-livekit-server,start-group-services

https://claude.ai/code/session_01SbRgWsRDKpTZ2TTbWDhtEB

livekit.yml

@@ -0,0 +1,15 @@
+---
+# Standalone playbook for LiveKit Server setup.
+# Use instead of setup.yml to avoid loading all unrelated galaxy roles.
+#
+# Usage:
+#   ansible-playbook -i inventory/hosts livekit.yml --tags=setup-livekit-server,start-group-services
+#
+- name: "Set up LiveKit Server"
+  hosts: "{{ target if target is defined else 'matrix_servers' }}"
+  become: true
+
+  roles:
+    - role: galaxy/systemd_docker_base
+
+    - role: custom/livekit_server

setup.yml

@@ -124,7 +124,7 @@
 
     - custom/matrix-element-admin
     - custom/matrix-element-call
-    - custom/livekit_server
+    - galaxy/livekit_server
     - custom/matrix-livekit-jwt-service
 
     - role: galaxy/postgres_backup