fix: Prevent brand theme flicker when clicking same NavLink repeatedly

Two issues resolved:

1. NavMenu.razor: Guard OnLocationChanged to only run when URL actually changes
   - Prevents unnecessary theme re-application on same-link clicks
   - Eliminates redundant StateHasChanged calls

2. theme.js: Optimize MutationObserver to only watch theme attributes
   - Changed from observing entire document.body with childList+subtree
   - Now only observes documentElement with attributeFilter
   - Prevents observer from firing on every Blazor NavLink re-render
   - Eliminates unnecessary reflow operations that caused visual flicker

The combination of these fixes ensures clicking the same NavLink multiple times
no longer causes the brand theme to temporarily switch to Bootstrap.

Author: CIS Guru

3-Aquiis.UI.Shared/wwwroot/js/theme.js

@@ -115,9 +115,9 @@ if (typeof localStorage !== "undefined") {
 
   // Start observing after a short delay to let Blazor initialize
   setTimeout(() => {
-    observer.observe(document.body, {
-      childList: true,
-      subtree: true,
+    observer.observe(document.documentElement, {
+      attributes: true,
+      attributeFilter: ["data-bs-theme", "data-brand-theme"],
     });
   }, 1000);
 

4-Aquiis.SimpleStart/Shared/Layout/NavMenu.razor

@@ -19,7 +19,7 @@
 
 <input type="checkbox" title="Navigation menu" class="navbar-toggler" />
 
-<div class="nav-scrollable" onclick="document.querySelector('.navbar-toggler').click()">
+<div class="nav-scrollable">
     <nav class="nav flex-column">
 
         <OrganizationAuthorizeView Roles="Owner,Administrator">
@@ -336,7 +336,13 @@
 
     private async void OnLocationChanged(object? sender, LocationChangedEventArgs e)
     {
-        currentUrl = NavigationManager.ToBaseRelativePath(e.Location);
+        var newUrl = NavigationManager.ToBaseRelativePath(e.Location);
+        
+        // Only update if URL actually changed (prevents visual glitch on same-link clicks)
+        if (newUrl == currentUrl)
+            return;
+            
+        currentUrl = newUrl;
 
         // Re-apply current theme and brand theme after navigation
         try