feat(public-nav): slim appbar to ARCHIVE + inline CUTS/SESSIONS/MIXES, drop GENRES and Tracks (8.I)

Desktop flattens the ARCHIVE popover into inline appbar links above the medium
breakpoint; mobile keeps the indented sub-list under ARCHIVE. GENRES and /tracks
removed from nav only — routes (GenresView, TracksView) remain reachable by URL.
Retires the now-dead desktop hover-popover and its 8.J collapse-state machinery
(mobile drawer still dismisses on click).

DeepDrftPublic.Client/Layout/DeepDrftMenu.razor

@@ -10,32 +10,17 @@
         <ul class="dd-nav-links">
             @foreach (var navPage in Pages.MenuPages)
             {
-                @if (navPage.HasChildren)
-                {
-                    @* Dual-role node: the parent anchor navigates to its own route on click,
-                       while hover/focus reveals the child dropdown (pure CSS, no JS).
-                       dd-nav-item-collapsed is added on child click to force-hide the
-                       dropdown after SPA navigation (which keeps the DOM and may leave
-                       :hover true). It is cleared on mouseleave so the next hover works. *@
-                    <li class="dd-nav-item-parent @(_collapsedDropdowns.Contains(navPage.Route) ? "dd-nav-item-collapsed" : "")"
-                        @onmouseleave="() => ResetDropdown(navPage.Route)"
-                        @onfocusout="() => ResetDropdown(navPage.Route)">
-                        <a href="@navPage.Route" class="dd-nav-link">@navPage.Name</a>
-                        <ul class="dd-nav-dropdown">
-                            @foreach (var child in navPage.Children)
-                            {
-                                <li>
-                                    <a href="@child.Route" class="dd-nav-link dd-nav-dropdown-link"
-                                       @onclick="() => CollapseDropdown(navPage.Route)">@child.Name</a>
-                                </li>
-                            }
-                        </ul>
-                    </li>
-                }
-                else
+                @* Above the medium breakpoint the medium modes ride inline beside their parent:
+                   the parent link renders, then each child renders as its own sibling appbar link.
+                   No popover — so the 8.J stuck-open dismissal applies only to the mobile drawer
+                   below, where clicks close the menu. *@
+                <li>
+                    <a href="@navPage.Route" class="dd-nav-link">@navPage.Name</a>
+                </li>
+                @foreach (var child in navPage.Children)
                 {
                     <li>
-                        <a href="@navPage.Route" class="dd-nav-link">@navPage.Name</a>
+                        <a href="@child.Route" class="dd-nav-link">@child.Name</a>
                     </li>
                 }
             }
@@ -96,7 +81,6 @@
     [Parameter] public required EventCallback<bool> IsDarkModeChanged { get; set; }
 
     private bool _mobileMenuOpen;
-    private readonly HashSet<string> _collapsedDropdowns = [];
 
     protected override async Task OnAfterRenderAsync(bool firstRender)
     {
@@ -129,8 +113,4 @@
     private void ToggleMobileMenu() => _mobileMenuOpen = !_mobileMenuOpen;
 
     private void CloseMobileMenu() => _mobileMenuOpen = false;
-
-    private void CollapseDropdown(string route) => _collapsedDropdowns.Add(route);
-
-    private void ResetDropdown(string route) => _collapsedDropdowns.Remove(route);
 }