fix: add matrix-base role to livekit.yml to resolve undefined variables

matrix_user_uid/gid, matrix_server_fqn_matrix, matrix_addons_container_network
are all defined by custom/matrix-base and required by livekit_server role.

https://claude.ai/code/session_01SbRgWsRDKpTZ2TTbWDhtEB

livekit.yml

@@ -12,4 +12,6 @@
   roles:
     - role: galaxy/systemd_docker_base
 
+    - role: custom/matrix-base
+
     - role: custom/livekit_server