ui : show the selected model of the compat backends
A compat backend serves the selection itself and reports no load state,
so the selected model sat inside its provider section, possibly cut off
by the display cap. Give it a leading section of its own, in the
selector list and the manager table, the way loaded models lead the
llama-compat ones.
Assisted-by: pi:llama.cpp/DeepSeek-V4.1-Flash
