feat(claude): add configurable API base URL via --anthropic-url

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

src/main.rs

@@ -20,6 +20,7 @@ async fn main() -> anyhow::Result<()> {
 
     tracing::info!("scout starting");
     tracing::info!("  swym API:    {}", cli.swym_url);
+    tracing::info!("  claude API:  {}", cli.anthropic_url);
     tracing::info!("  model:       {}", cli.model);
     tracing::info!("  iterations:  {}", cli.max_iterations);
     tracing::info!("  instruments: {:?}", cli.instruments);