Preserve platform order list context via back param links

tests/Feature/AdminPlatformOrderIndexOrderNoLinkWithBackTest.php

@@ -0,0 +1,62 @@
+<?php
+
+namespace Tests\Feature;
+
+use Illuminate\Foundation\Testing\RefreshDatabase;
+use Tests\TestCase;
+
+class AdminPlatformOrderIndexOrderNoLinkWithBackTest extends TestCase
+{
+    use RefreshDatabase;
+
+    protected function loginAsPlatformAdmin(): void
+    {
+        $this->seed();
+
+        $this->post('/admin/login', [
+            'email' => 'platform.admin@demo.local',
+            'password' => 'Platform@123456',
+        ])->assertRedirect('/admin');
+    }
+
+    public function test_order_no_link_in_index_contains_back_param(): void
+    {
+        $this->loginAsPlatformAdmin();
+
+        $merchant = \App\Models\Merchant::query()->firstOrFail();
+        $plan = \App\Models\Plan::query()->create([
+            'code' => 'po_index_back_plan_01',
+            'name' => '平台订单列表 back 参数测试套餐',
+            'billing_cycle' => 'monthly',
+            'price' => 10,
+            'list_price' => 10,
+            'status' => 'active',
+            'sort' => 10,
+            'published_at' => now(),
+        ]);
+
+        $order = \App\Models\PlatformOrder::query()->create([
+            'merchant_id' => $merchant->id,
+            'plan_id' => $plan->id,
+            'order_no' => 'PO_INDEX_BACK_0001',
+            'order_type' => 'new_purchase',
+            'status' => 'pending',
+            'payment_status' => 'unpaid',
+            'plan_name' => $plan->name,
+            'billing_cycle' => $plan->billing_cycle,
+            'period_months' => 1,
+            'quantity' => 1,
+            'payable_amount' => 10,
+            'paid_amount' => 0,
+            'placed_at' => now(),
+            'meta' => [],
+        ]);
+
+        // index 页应存在该订单行链接，且链接带 back（保留筛选上下文）
+        $res = $this->get('/admin/platform-orders?status=pending');
+        $res->assertOk();
+
+        $expectedBack = urlencode('/admin/platform-orders?status=pending');
+        $res->assertSee('/admin/platform-orders/' . $order->id . '?back=' . $expectedBack, false);
+    }
+}