Implement search to narrow down list of models

I added openrouter API in "Others" (because original set is very limited) and then tried to select a model.

The app fetches all available models but I cannot search and filter, which means I have to go through all the models one by one to select my preferred model.

There are approximately 100 models I need to search through (UNORDERED 😢 )

Also Openrouter model list is very restricted. This is raised in another issue here