feat: mobile auto-hide header and tabs for multi-session terminal

- Add useAutoHide hook to TerminalPage for mobile header/tab strip
- Header and tabs auto-hide after 3s, tap to reveal
- Add CSS transitions for smooth show/hide on mobile
- Fullscreen mobile mode hides header and tabs completely

apps/web/src/styles.css

@@ -2904,6 +2904,25 @@ a.nav-item,
 	opacity: 1;
 }
 
+/* Mobile auto-hide header and tabs */
+.terminal-page.mobile .terminal-page-header,
+.mobile-tabs-container {
+	transition: transform 0.3s ease, opacity 0.3s ease;
+}
+
+.terminal-page.mobile .terminal-page-header.hidden,
+.mobile-tabs-container.hidden {
+	transform: translateY(-100%);
+	opacity: 0;
+	pointer-events: none;
+}
+
+.terminal-page.mobile .terminal-page-header.visible,
+.mobile-tabs-container.visible {
+	transform: translateY(0);
+	opacity: 1;
+}
+
 /* Mobile fullscreen */
 @media (max-width: 767px) {
 	.terminal-page.fullscreen {