fix(js): reload stale popstate partials

When back/forward navigation receives an incompatible or unusable partial response, reload the current URL instead of leaving the previous UI stale.

req: page_swap/005

req: page_swap/006

req: runtime/004

slhx-js/tests/runtime.rs

@@ -145,7 +145,16 @@ fn runtime_exposes_page_swap_hooks() {
     assert!(source.contains("x-slhx-title"));
     assert!(source.contains("x-slhx-fingerprint"));
     assert!(source.contains("slhx:missing-content-slot"));
-    assert!(source.contains("location.href = href"));
+    assert!(source.contains("else location.href = href"));
+}
+
+#[test]
+fn runtime_popstate_failed_partials_reload_instead_of_stale_ui() {
+    // req: page_swap/005 req: page_swap/006 req: runtime/004
+    let source = slhx_js::RUNTIME_JS;
+
+    assert!(source.contains("if (mode === \"none\") location.reload();"));
+    assert!(source.contains("if (root) navigateUrl(location.href, root, \"none\")"));
 }
 
 #[test]