fix(ui): improve dark-mode loading contrast and remove header borders

Use the warning accent for dark-mode loading indicators and simplify desktop navigation chrome by removing sidebar and top-bar separator borders. Add regression coverage for loading contrast and checkpoint spinner markup.

tests/Feature/CheckpointItemContrastTest.php

@@ -0,0 +1,10 @@
+<?php
+
+it('uses the high contrast accent for a running checkpoint spinner', function () {
+    $view = $this->blade('<x-checkpoint-item title="Server is reachable" status="running" />');
+
+    $view
+        ->assertSee('dark:text-warning', false)
+        ->assertSee('animate-spin', false)
+        ->assertDontSee('spinner-current', false);
+});

tests/Feature/LivewireLoadingColorTest.php

@@ -1,20 +1,19 @@
 <?php
 
-test('loading indicators use coollabs purple throughout dark mode', function () {
+test('loading indicators use warning yellow throughout dark mode', function () {
     $utilities = file_get_contents(resource_path('css/utilities.css'));
     $appCss = file_get_contents(resource_path('css/app.css'));
     $loading = file_get_contents(resource_path('views/components/loading.blade.php'));
     $pageLoading = file_get_contents(resource_path('views/components/page-loading.blade.php'));
     expect($utilities)
         ->toContain('@utility loading-indicator')
-        ->toContain('@apply text-coollabs dark:text-coollabs;')
+        ->toContain('@apply text-coollabs dark:text-warning;')
         ->and($loading)->toContain('loading-indicator')
         ->and($pageLoading)->toContain('loading-indicator')
         ->and($appCss)->toContain('.dark .animate-spin')
-        ->toContain('color: var(--color-coollabs) !important;')
+        ->toContain('color: var(--color-warning) !important;')
         ->toContain('.dark #nprogress .bar')
-        ->toContain('background: var(--color-coollabs) !important;')
-        ->not->toContain('color: var(--color-warning) !important;');
+        ->toContain('background: var(--color-warning) !important;');
 });
 
 test('livewire navigation progress bar uses coollabs purple', function () {

tests/Feature/SidebarNavigationMarkupTest.php

@@ -57,6 +57,22 @@ it('draws a single border between the desktop sidebar and main content', functio
         ->and($layout)->not->toContain('lg:border-l border-neutral-200');
 });
 
+it('does not separate the desktop sidebar controls with a top border', function () {
+    $navbar = file_get_contents(resource_path('views/components/navbar.blade.php'));
+
+    expect($navbar)
+        ->toContain('sticky bottom-0 mt-auto -mx-2 hidden items-center gap-1 bg-white')
+        ->not->toContain('sticky bottom-0 mt-auto -mx-2 hidden items-center gap-1 border-t');
+});
+
+it('does not draw a bottom border below the desktop top bar', function () {
+    $layout = file_get_contents(resource_path('views/layouts/app.blade.php'));
+
+    expect($layout)
+        ->toContain('fixed top-0 inset-x-0 z-50 h-12 items-center bg-white/95 dark:bg-panel/95 backdrop-blur')
+        ->not->toContain('backdrop-blur border-b border-neutral-200 dark:border-white/[0.06]');
+});
+
 it('separates the mobile sidebar from the page with a visible border', function () {
     $layout = file_get_contents(resource_path('views/layouts/app.blade.php'));