Fix sidebar dropdown direction and accidental mobile drawer opening

- CSS: When sidebar is collapsed, open user-menu dropdown to the right
  (left: 0, right: auto) via data-sidebar-expanded="false" selector.
- JS: Guard drawerToggle change handler – prevent mobile drawer from
  opening on desktop viewports (window.innerWidth >= 1024).
- HTML: Add phx-update="ignore" to mobile-drawer checkbox to prevent
  LiveView from resetting its checked state on DOM patches.

assets/js/app.js

@@ -228,6 +228,13 @@ document.addEventListener("DOMContentLoaded", () => {
   
   // Listen for changes to the drawer checkbox
   drawerToggle.addEventListener("change", () => {
+    // On desktop (lg:drawer-open), the mobile drawer must never open.
+    // The hamburger label is lg:hidden, but guard here as a safety net
+    // against any accidental toggles (e.g. from overlapping elements or JS).
+    if (drawerToggle.checked && window.innerWidth >= 1024) {
+      drawerToggle.checked = false
+      return
+    }
     const isOpen = drawerToggle.checked
     updateAriaExpanded()
     updateSidebarTabIndex(isOpen)