only show ollama when installed

[michaelneale]

this detects ollama and shows the card only when it is installed

another take on #4329 cc @blackgirlbytes @angiejones

(currently is down below the fold, and mentions significant hardware requirements)

[angiejones]

would prefer #4348. just because Ollama is installed doesnt mean the user has a model that is good for tool calling. it's just overall not the best experience

[michaelneale]

@angiejones given how much I Have been pinged about the regression (with streaming) from 1.5, I think a lot more are using it than we realise. This change won't show it unless running, and will check for the model/download the prescribed one if they choose to go that path (otherwise they are more likely to get the generic ollama case and use a model we don't know will work).

[michaelneale]

closing as was removed instead