feat: add temperature, top_p, top_k, min_p params to insight generation

Expose Ollama sampling params through the insight generation endpoints
so users can tune creativity/determinism per request. All four are
optional — omitted values fall through to the model's server-side
defaults.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/bin/populate_knowledge.rs

@@ -202,6 +202,10 @@ async fn main() -> anyhow::Result<()> {
                 args.model.clone(),
                 None,
                 args.num_ctx,
+                None,
+                None,
+                None,
+                None,
                 args.max_iterations,
             )
             .await