Enhance: platform order create flow carries back and redirects with back

resources/views/admin/platform_orders/form.blade.php

@@ -23,6 +23,7 @@
     @csrf
 
     <input type="hidden" name="site_subscription_id" value="{{ old('site_subscription_id', $defaults['site_subscription_id'] ?? '') }}">
+    <input type="hidden" name="back" value="{{ old('back', $defaults['back'] ?? '') }}">
 
     <label>
         <span>站点</span>
@@ -79,7 +80,17 @@
     </label>
 
     <div class="form-actions">
-        <a href="/admin/platform-orders" class="btn-secondary">返回</a>
+        @php
+            $incomingBack = (string) ($defaults['back'] ?? '');
+            $safeBack = str_starts_with($incomingBack, '/') ? $incomingBack : '';
+        @endphp
+
+        @if($safeBack)
+            <a href="{{ $safeBack }}" class="btn-secondary">返回（保留上下文）</a>
+        @else
+            <a href="/admin/platform-orders" class="btn-secondary">返回</a>
+        @endif
+
         <button type="submit">创建订单</button>
     </div>
 </form>