feat: improve Monitor panel UX and preserve session names

- Monitor panel now opens by default on webapp start
- Replace "Reconcile" button with refresh icon (↻)
- Change close button to toggle (▼/▲) for collapse/expand
- Preserve session display names when saving screen info
- Use stored name when restoring sessions (no more "Restored:" prefix)
- Show session name in Monitor panel instead of screen name
- Kill screen session when closing a tab

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/web/public/index.html

@@ -135,8 +135,8 @@
       <div class="monitor-panel-header">
         <span>Monitor</span>
         <div class="monitor-panel-actions">
-          <button class="btn-toolbar btn-sm" onclick="app.reconcileScreens()" title="Check for dead screens">Reconcile</button>
-          <button class="btn-close" onclick="app.toggleMonitorPanel()">&times;</button>
+          <button class="btn-icon-sm" onclick="app.reconcileScreens()" title="Refresh screens">&#x21BB;</button>
+          <button class="btn-icon-sm" onclick="app.toggleMonitorPanel()" title="Toggle panel" id="monitorToggleBtn">&#x25BC;</button>
         </div>
       </div>
       <div class="monitor-panel-body">