feat: improve web UI UX with global search, breadcrumbs, and better feedback

cmd/web-ui/static/index.html

@@ -18,10 +18,15 @@
     </div>
     <nav><a href="/">Dashboard</a><a href="/sessions">Sessions</a><a href="/agents">Agents</a><a href="/infrastructure">Infra</a></nav>
     <div class="header-right">
+      <div class="header-search">
+        <input type="text" id="global-search" placeholder="Search ID..." spellcheck="false" autocomplete="off">
+        <kbd>/</kbd>
+      </div>
       <span class="ws-dot" id="ws-dot" title="Disconnected"></span>
       <button class="theme-toggle" id="theme-toggle" aria-label="Toggle theme"></button>
     </div>
   </header>
+  <div id="breadcrumbs" class="breadcrumbs"></div>
   <main id="app">
     <p>Loading...</p>
   </main>