fix(mobile): prevent menu tap from triggering unintended dashboard navigation

The mobile sidebar menu button redirects users to `cloudcli.ai/dashboard` when a
session was active. The redirect happened because
the menu was opened on `touchstart`, which mounted the sidebar before the touch
sequence completed; the follow-up tap/click then landed on the sidebar header
anchor.

This change rewrites mobile menu interaction handling in `MainContent.jsx` to
eliminate touch/click event leakage and ghost-click behavior.

Key changes:
- Added `suppressNextMenuClickRef` to guard against synthetic click events that
  fire after a touch interaction.
- Added `openMobileMenu(event)` helper to centralize `preventDefault`,
  `stopPropagation`, and `onMenuClick()` invocation.
- Added `handleMobileMenuTouchEnd(event)`:
  - opens the menu on `touchend` instead of `touchstart`
  - sets a short suppression window (350ms) for the next click.
- Added `handleMobileMenuClick(event)`:
  - ignores/suppresses click events during the suppression window
  - otherwise opens the menu normally.
- Updated all mobile menu button instances in `MainContent.jsx` (loading state,
  no-project state, active header state) to use:
  - `onTouchEnd={handleMobileMenuTouchEnd}`
  - `onClick={handleMobileMenuClick}`
- Removed the previous `onTouchStart` path that caused premature DOM mutation.

Behavioral impact:
- Mobile sidebar still opens reliably with one tap.
- Tap no longer leaks to newly-mounted sidebar header links.
- Prevents accidental redirects while preserving existing menu UX.

src/components/MainContent.jsx

@@ -63,6 +63,7 @@ function MainContent({
   const [isResizing, setIsResizing] = useState(false);
   const [editorExpanded, setEditorExpanded] = useState(false);
   const resizeRef = useRef(null);
+  const suppressNextMenuClickRef = useRef(false);
 
   const { preferences } = useUiPreferences();
   const { autoExpandTools, showRawParameters, showThinking, autoScrollToBottom, sendByCtrlEnter } = preferences;
@@ -164,6 +165,34 @@ function MainContent({
     refreshTasks?.();
   };
 
+  const openMobileMenu = (event) => {
+    if (event) {
+      event.preventDefault();
+      event.stopPropagation();
+    }
+
+    onMenuClick();
+  };
+
+  const handleMobileMenuTouchEnd = (event) => {
+    suppressNextMenuClickRef.current = true;
+    openMobileMenu(event);
+
+    window.setTimeout(() => {
+      suppressNextMenuClickRef.current = false;
+    }, 350);
+  };
+
+  const handleMobileMenuClick = (event) => {
+    if (suppressNextMenuClickRef.current) {
+      event.preventDefault();
+      event.stopPropagation();
+      return;
+    }
+
+    openMobileMenu(event);
+  };
+
   // Handle resize functionality
   const handleMouseDown = (e) => {
     if (isMobile) return; // Disable resize on mobile
@@ -218,7 +247,8 @@ function MainContent({
             className="bg-background border-b border-border p-2 sm:p-3 pwa-header-safe flex-shrink-0"
           >
             <button
-              onClick={onMenuClick}
+              onClick={handleMobileMenuClick}
+              onTouchEnd={handleMobileMenuTouchEnd}
               className="p-2 text-gray-600 dark:text-gray-400 hover:text-gray-900 dark:hover:text-white rounded-md hover:bg-gray-100 dark:hover:bg-gray-700 pwa-menu-button"
             >
               <svg className="w-5 h-5" fill="none" stroke="currentColor" viewBox="0 0 24 24">
@@ -256,7 +286,8 @@ function MainContent({
             className="bg-background border-b border-border p-2 sm:p-3 pwa-header-safe flex-shrink-0"
           >
             <button
-              onClick={onMenuClick}
+              onClick={handleMobileMenuClick}
+              onTouchEnd={handleMobileMenuTouchEnd}
               className="p-2 text-gray-600 dark:text-gray-400 hover:text-gray-900 dark:hover:text-white rounded-md hover:bg-gray-100 dark:hover:bg-gray-700 pwa-menu-button"
             >
               <svg className="w-5 h-5" fill="none" stroke="currentColor" viewBox="0 0 24 24">
@@ -297,11 +328,8 @@ function MainContent({
           <div className="flex items-center space-x-2 min-w-0 flex-1">
             {isMobile && (
               <button
-                onClick={onMenuClick}
-                onTouchStart={(e) => {
-                  e.preventDefault();
-                  onMenuClick();
-                }}
+                onClick={handleMobileMenuClick}
+                onTouchEnd={handleMobileMenuTouchEnd}
                 className="p-2 text-gray-600 dark:text-gray-400 hover:text-gray-900 dark:hover:text-white rounded-md hover:bg-gray-100 dark:hover:bg-gray-700 touch-manipulation active:scale-95 pwa-menu-button flex-shrink-0"
               >
                 <svg className="w-5 h-5" fill="none" stroke="currentColor" viewBox="0 0 24 24">
@@ -682,4 +710,4 @@ function MainContent({
   );
 }
 
-export default React.memo(MainContent);
+export default React.memo(MainContent);