The merge model picker was reusing chatViewModel.availableModels,
which only ever holds whichever provider the main chat window
currently has active — fine for the main chat's own switcher (where
provider and model change together via the header), wrong for an
independent one-off picker like this. If your active chat was on
Anthropic, that's all you could pick from here regardless of what
other providers you have configured.
Added its own provider menu (mirroring HeaderView's) and an
independent model list fetched via ProviderRegistry for whichever
provider is selected, so OpenRouter, Anthropic, OpenAI, etc. are all
genuinely selectable regardless of what the main chat is doing.