fix(maestro): render ☰ on mobile empty state

The welcome/empty-tab branch returned before renderMobile, so with the tab
bar collapsed there was no ☰ — leaving mobile users stuck with no way to
open the sidebar drawer. Float the same ☰ over the welcome view.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

web/src/multiview.ts

@@ -338,6 +338,18 @@ export function createMultiView(opts: MultiViewOptions): MultiView {
     render();
   }
 
+  // The floating ☰ that stands in for the collapsed tab bar on mobile (single
+  // tab), keeping the sidebar drawer reachable from the welcome + pane views.
+  function makeMobileFab(): HTMLButtonElement {
+    const fab = document.createElement("button");
+    fab.type = "button";
+    fab.className = "mv-mobile-fab";
+    fab.title = "Sessions";
+    fab.textContent = "☰";
+    fab.addEventListener("click", () => opts.onToggleSidebar?.());
+    return fab;
+  }
+
   // ---- top-level render ----
 
   function render(): void {
@@ -351,6 +363,7 @@ export function createMultiView(opts: MultiViewOptions): MultiView {
     if (!tab.root) {
       pool.setVisible([]);
       pool.setFocus(null);
+      if (isMobile && layout.tabs.length === 1) canvas.appendChild(makeMobileFab());
       canvas.appendChild(renderWelcome());
       sidebar.setHighlights({ open: openSessions(layout), focused: null, colors: colorMap() });
       persist();
@@ -385,15 +398,7 @@ export function createMultiView(opts: MultiViewOptions): MultiView {
 
     // With a single tab the tab bar (and its ☰) is hidden — float a ☰ so the
     // sidebar drawer stays reachable.
-    if (layout.tabs.length === 1) {
-      const fab = document.createElement("button");
-      fab.type = "button";
-      fab.className = "mv-mobile-fab";
-      fab.title = "Sessions";
-      fab.textContent = "☰";
-      fab.addEventListener("click", () => opts.onToggleSidebar?.());
-      wrap.appendChild(fab);
-    }
+    if (layout.tabs.length === 1) wrap.appendChild(makeMobileFab());
 
     if (ls.length > 1) {
       const bar = document.createElement("div");