feat: add search user page with push notification service worker support

Add SearchUserView with HTML and JSON endpoints, create search-user.html template extending app.html with navigation link, implement push.js for service worker registration and push subscription handling, add service-worker.js for push event display and notification click handling, and fix install prompt event listener registration in app.html

src/snek/templates/app.html

@@ -24,6 +24,7 @@
     <div class="logo">Snek</div>
     <nav>
       <a href="/web.html">🏠</a>
+      <a href="/search-user.html">🔍</a>
       <a style="display:none" id="install-button" href="#">📥</a>
       <a href="/web.html">👥</a>
       <a href="#">⚙️</a>
@@ -52,7 +53,7 @@ let installPrompt = null
         window.addEventListener("beforeinstallprompt", async(event) => {
             event.preventDefault();
             installPrompt = event;
-            //document.addEventListener("DOMContentLoaded", () => {
+            document.addEventListener("DOMContentLoaded", () => {
             alert("Jaaah") 
             const button = document.getElementById("install-button")
             button.addEventListener("click", async ()=>{  
@@ -61,7 +62,8 @@ let installPrompt = null
             })
             button.style.display = 'inline-block'
             
-          });
+            })
+        });
         ;
     </script>
 </body>