Pi's Edit() only set baseUrl when creating a new ollama provider entry.
On subsequent launches it preserved whatever baseUrl was already in
~/.pi/agent/models.json, so switching OLLAMA_HOST to a remote server had
no effect — Pi would still connect to localhost.
Edit() now ensures baseUrl reflects the current OLLAMA_HOST. Models()
returns nil when the stored baseUrl no longer matches, so the launcher
only calls Edit() when the host has actually drifted. User-customized api
and apiKey fields are still preserved.