feat: plans index add create order quick link

tests/Feature/AdminPlanIndexCreateOrderLinkTest.php

@@ -0,0 +1,66 @@
+<?php
+
+namespace Tests\Feature;
+
+use App\Models\Plan;
+use Illuminate\Foundation\Testing\RefreshDatabase;
+use Illuminate\Support\Arr;
+use Tests\TestCase;
+
+class AdminPlanIndexCreateOrderLinkTest 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_plan_index_should_render_create_order_link_with_plan_id_and_back(): void
+    {
+        $this->loginAsPlatformAdmin();
+
+        $plan = Plan::query()->create([
+            'code' => 'plan_create_order_link_test',
+            'name' => '套餐创建订单链接测试',
+            'billing_cycle' => 'monthly',
+            'price' => 99,
+            'list_price' => 99,
+            'status' => 'active',
+            'sort' => 1,
+            'published_at' => now(),
+        ]);
+
+        // 访问列表页时带 back（模拟来自别处），链接 back 应回到 selfWithoutBack（去掉 back）
+        $currentUrl = '/admin/plans?' . Arr::query([
+            'status' => 'active',
+            'billing_cycle' => 'monthly',
+            'back' => '/admin',
+        ]);
+
+        $res = $this->get($currentUrl);
+        $res->assertOk();
+
+        $selfWithoutBack = '/admin/plans?' . Arr::query([
+            'status' => 'active',
+            'billing_cycle' => 'monthly',
+        ]);
+
+        $expectedCreateUrl = '/admin/platform-orders/create?' . Arr::query([
+            'plan_id' => $plan->id,
+            'order_type' => 'new_purchase',
+            'back' => $selfWithoutBack,
+        ]);
+
+        $res->assertSee($expectedCreateUrl, false);
+        $res->assertSee('创建订单', false);
+
+        // 防 back 嵌套
+        $res->assertDontSee('back%3D', false);
+    }
+}