ui : show every provider's models in the manager
The table grows a section per enabled provider, each with its own mark,
error and loading state, and a provider filter with live repo counts.
Rows gain their capability gates back, the draft column with its
use-as-draft action, and the quant badge names the provider on its rows.
Assisted-by: pi:llama.cpp/DeepSeek-V4.1-Flash
