fix: improve config schema and serve from docs site (#1248)

Fix idleTimeout description to document human-friendly formats (30s,
5m, 1h) alongside raw milliseconds. Add trailing newline. Serve the
schema from the docs app at agent-browser.dev/schema.json via a
prebuild copy step, and update all $schema URLs to use the stable
docs-hosted URL instead of raw GitHub.

cli/src/native/browser.rs

@@ -1302,10 +1302,8 @@ async fn poll_network_idle(
                                 }
                             }
                         }
-                        "Page.loadEventFired" => {
-                            if p.is_empty() {
-                                idle_start = Some(tokio::time::Instant::now());
-                            }
+                        "Page.loadEventFired" if p.is_empty() => {
+                            idle_start = Some(tokio::time::Instant::now());
                         }
                         _ => {}
                     }