fix(router): forward streamed Suspense resolvers on same-layout nav

Streamed Suspense templates (<template data-webjs-resolve="...">) are
emitted at body level, AFTER the </div> that closes the data-layout
wrapper. During same-layout navigation the router swaps only the
<main> contents inside the wrapper, so those resolvers were dropped
and the fallback stayed frozen ("computing timestamp…" forever).

Forward them explicitly: after the swap, query the fetched body for
template[data-webjs-resolve] and append clones onto the live body.
The suspense boot's MutationObserver picks them up automatically.

Author: vivek7405

packages/core/src/router-client.js

@@ -221,6 +221,10 @@ async function performNavigation(href, isPopState) {
         (n) => !(n instanceof HTMLTemplateElement && /** @type any */ (n).getAttribute('shadowrootmode'))
       );
       swapSlotContent(target, children);
+      // Forward any streamed Suspense resolvers that sit outside the layout
+      // wrapper (they're emitted at body level, after </div>). Without this,
+      // the new page's fallback boundary never gets its deferred content.
+      forwardSuspenseResolvers(doc.body);
     } else {
       // Different layout structure — full swap.
       // Move nodes directly from the parsed doc (preserves DSD shadow roots)
@@ -434,6 +438,21 @@ function upgradeTree(root) {
   }
 }
 
+/**
+ * Copy streamed Suspense resolver templates + scripts from the fetched
+ * document body onto the live document body. The `<template>` elements carry
+ * a `data-webjs-resolve="<id>"` attribute; the suspense boot's
+ * MutationObserver watches for them and replaces the matching
+ * `<webjs-boundary id="<id>">` with the template content.
+ *
+ * @param {HTMLElement} fetchedBody
+ */
+function forwardSuspenseResolvers(fetchedBody) {
+  for (const tpl of fetchedBody.querySelectorAll('template[data-webjs-resolve]')) {
+    document.body.appendChild(tpl.cloneNode(true));
+  }
+}
+
 /** Re-run `<script>` tags in a container (innerHTML doesn't execute them). */
 function reactivateScripts(container) {
   for (const old of container.querySelectorAll('script')) {