feat(runtime): run local shell commands from UI

ui/app.js

@@ -136,6 +136,30 @@ function wireVaultActions() {
   if (button) button.addEventListener('click', saveDemoVault);
 }
 
+async function runLocalTerminalCommand() {
+  const command = document.getElementById('terminal-command').value;
+  const output = document.getElementById('terminal-output');
+  output.textContent = 'Running…';
+  try {
+    const tauri = window.__TAURI__?.core;
+    if (!tauri) throw new Error('Tauri bridge unavailable in browser preview');
+    const result = await tauri.invoke('run_local_command', { command, cwd: null });
+    output.textContent = [
+      `$ ${command}`,
+      `exit ${result.exit_code}`,
+      result.stdout ? `stdout:\n${result.stdout}` : '',
+      result.stderr ? `stderr:\n${result.stderr}` : ''
+    ].filter(Boolean).join('\n');
+  } catch (error) {
+    output.textContent = String(error);
+  }
+}
+
+function wireTerminalActions() {
+  const button = document.getElementById('run-terminal');
+  if (button) button.addEventListener('click', runLocalTerminalCommand);
+}
+
 async function boot() {
   const [dashboard, features] = await Promise.all([
     invokeOrFallback('wallet_dashboard', fallbackDashboard),
@@ -144,6 +168,7 @@ async function boot() {
   renderDashboard(dashboard);
   renderFeatures(features);
   wireVaultActions();
+  wireTerminalActions();
 }
 
 boot();