Function check_ollama_connectivity 

pub async fn check_ollama_connectivity(base_url: &str) -> bool

Ping the Ollama endpoint to verify it is reachable.

Issues a lightweight GET /api/tags with a short timeout. Returns true only on a successful HTTP response.

Arguments

• base_url – Ollama base URL (e.g. http://localhost:11434). Falls back to DEFAULT_OLLAMA_BASE_URL when empty.