tools: Centralize GPU group setup via setup_hwaccel (#13044)

improve hardware-acceleration setup to centralize service user group management. Install scripts (emby, plex, ollama, channels) now pass a service user to setup_hwaccel (or no user for channels) and have had inline /etc/group sed/usermod tweaks removed. misc/tools.func updated: setup_hwaccel accepts an optional service_user and forwards it to _setup_gpu_permissions, which now adds the service user to render and video groups if provided. This consolidates GPU permission changes in one place and removes duplicated per-service group edits.

install/channels-install.sh

@@ -35,7 +35,6 @@ setup_hwaccel
 msg_info "Installing Channels DVR Server (Patience)"
 cd /opt
 $STD bash <(curl -fsSL https://getchannels.com/dvr/setup.sh)
-sed -i -e 's/^sgx:x:104:$/render:x:104:root/' -e 's/^render:x:106:root$/sgx:x:106:/' /etc/group
 msg_ok "Installed Channels DVR Server"
 
 motd_ssh