feat(host): wire techdemo host capability flow

Route browser/PWA share and native-shell haptic host results through techdemo app code before returning normal hemx effects; serve the tiny browser host adapter as an app asset.

req: host/001

req: host/002

req: host/004

req: host/005

req: examples/001

examples/techdemo/templates/app_shell.heml

@@ -5,6 +5,7 @@
   <meta name="viewport" content="width=device-width, initial-scale=1">
   <title>hemx Techdemo</title>
   <script +src="self.runtime_src" defer></script>
+  <script src="/hemx-browser-host.js" defer></script>
   <script src="/island.js" defer></script>
   <link rel="stylesheet" href="/app.css">
   <link rel="stylesheet" href="/control_center.css">

examples/techdemo/templates/control_center.heml

@@ -32,6 +32,7 @@
         <button type="button" data-hemx-handle="simulate_push">Simulate server push</button>
         <button type="button" data-hemx-handle="reset_demo">Reset demo</button>
       </div>
+      <div data-hemx-slot="host_panel">{+= self.host =+}</div>
       <p data-hemx-slot="notice" class="notice">Every control posts through a generated handle and receives typed updates.</p>
     </aside>
 

examples/techdemo/templates/partials/host_panel.heml

@@ -0,0 +1,10 @@
+<div class="host-panel">
+  <p><strong>Typed host boundary</strong><br>{+ self.status +}</p>
+  <div class="quick-actions">
+    <button type="button" data-hemx-handle="request_browser_share">Request browser/PWA share</button>
+    <button type="button" data-hemx-handle="record_browser_share" name="completed" value="true">Record browser share result</button>
+    <button type="button" data-hemx-handle="request_native_haptic">Request native haptic</button>
+    <button type="button" data-hemx-handle="record_native_haptic_ack">Record native haptic ack</button>
+  </div>
+  <code>{+ self.boundary +}</code>
+</div>