Simplify admin nav: merge channel entry into system

resources/views/admin/layouts/app.blade.php

@@ -40,7 +40,6 @@
         <details class="nav-group" open>
             <summary class="nav-group-title">系统</summary>
             <a href="/admin/settings/system" class="nav-item nav-item--sub">系统配置</a>
-            <a href="/admin/settings/channels" class="nav-item nav-item--sub">渠道配置</a>
         </details>
 
         <div class="group-title">外部入口</div>

resources/views/admin/settings/system.blade.php

@@ -8,6 +8,10 @@
     <p class="mt-0">系统配置已经从静态骨架切到数据库读取，当前已支持基础编辑、保存和缓存刷新。</p>
     <div class="muted">当前系统配置列表已接入缓存读取。</div>
     <div class="muted">当前配置分组数：{{ $groupedCount }}</div>
+
+    <div class="actions mt-12">
+        <a class="btn btn-secondary" href="/admin/settings/channels">渠道与支付配置</a>
+    </div>
 </div>
 
 @foreach($systemSettings->groupBy('group') as $group => $items)