perf(bfcache): rehydrate UI on back/forward cache restore\n\n- Add pageshow handler to re-init Search/Theme/ToC/Math/Mermaid\n- Dispatch app:rehydrate for future hooks

Author: kascit

templates/index.html

@@ -246,6 +246,24 @@
             });
         </script>
         {% endif %}
+
+        <script>
+            // Rehydrate on back/forward cache restore
+            window.addEventListener('pageshow', function (event) {
+                if (event.persisted) {
+                    try {
+                        if (typeof initSearch === 'function') initSearch();
+                        if (typeof initTheme === 'function') initTheme();
+                        if (typeof initToc === 'function') initToc();
+                        if (typeof initMath === 'function') initMath();
+                        if (typeof window.initMermaid === 'function') window.initMermaid();
+                        document.dispatchEvent(new Event('app:rehydrate'));
+                    } catch (err) {
+                        console.warn('bfcache rehydrate failed:', err);
+                    }
+                }
+            });
+        </script>
     {% endblock js_body %}
 </body>
 </html>