feat: 商城付费购买流 + 市场契约

- MarketPackage 模型/迁移：市场商品作为可购买实体（payable），复用 Payment 订单
- MarketPurchaseService：购买创建订单、已购判断、免费/付费门槛校验
- payment.paid 监听（核心注册，仅支付插件启用时）标记商品已购
- 市场契约：条目含 name/type/price（分）/download_url；插件市场 Tab 只显示 plugin、主题市场 Tab 只显示 theme；付费商品显示「购买」按钮与「已购买」徽章，未购买无法安装
- 新增主题市场 Tab（原仅插件页有市场）
- 测试：购买/沙箱支付标记已购/重复购买/安装门槛/免费条目/支付插件禁用

app/Blog/Services/MarketPurchaseService.php

@@ -0,0 +1,114 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Blog\Services;
+
+use App\Blog\Support\PluginManager;
+use App\Models\MarketPackage;
+use Plugins\Neatstudio\Payment\Models\Payment;
+use Plugins\Neatstudio\Payment\Services\PaymentManager;
+use RuntimeException;
+
+class MarketPurchaseService
+{
+    public function __construct(private PluginManager $plugins, private PaymentManager $payment)
+    {
+    }
+
+    /**
+     * 市场条目键：优先 item.name，缺省用下载文件名。
+     */
+    public function itemKey(array $item): string
+    {
+        $name = $item['name'] ?? null;
+
+        if ($name) {
+            return (string) $name;
+        }
+
+        return basename((string) ($item['download_url'] ?? ''), '.zip') ?: uniqid('item-');
+    }
+
+    public function itemType(array $item): string
+    {
+        return $item['type'] ?? 'plugin';
+    }
+
+    public function requiresPayment(array $item): bool
+    {
+        return (int) ($item['price'] ?? 0) > 0;
+    }
+
+    /**
+     * 购买市场商品：创建订单并返回（null = 已购买过，无需重复支付）。
+     */
+    public function purchase(array $item): ?Payment
+    {
+        if (! $this->plugins->isEnabled('neatstudio.payment')) {
+            throw new RuntimeException('付费市场商品需要启用支付插件');
+        }
+
+        $price = (int) ($item['price'] ?? 0);
+
+        if ($price <= 0) {
+            throw new RuntimeException('该商品免费，无需购买');
+        }
+
+        $key = $this->itemKey($item);
+        $type = $this->itemType($item);
+        $user = auth()->user();
+
+        $package = MarketPackage::query()->firstOrCreate(
+            ['item_key' => $key, 'item_type' => $type],
+            [
+                'title' => (string) ($item['title'] ?? $key),
+                'price' => $price,
+                'status' => 'pending',
+                'user_id' => $user?->id,
+            ]
+        );
+
+        if ($package->isPaid()) {
+            return null;
+        }
+
+        return $this->payment->createOrder(
+            $user ?? $this->systemUser(),
+            '购买商品：'.$package->title,
+            $price,
+            $package,
+            'alipay'
+        );
+    }
+
+    public function isPurchased(string $key, string $type = 'plugin'): bool
+    {
+        return MarketPackage::query()
+            ->where('item_key', $key)
+            ->where('item_type', $type)
+            ->where('status', 'paid')
+            ->exists();
+    }
+
+    /**
+     * 校验市场条目可否安装：免费直接装，付费需已购买。
+     */
+    public function assertCanInstall(array $item): void
+    {
+        if ($this->requiresPayment($item) && ! $this->isPurchased($this->itemKey($item), $this->itemType($item))) {
+            throw new RuntimeException('该商品为付费商品，请先购买后再安装');
+        }
+    }
+
+    private function systemUser(): \App\Models\User
+    {
+        $user = \App\Models\User::query()->first();
+
+        if (! $user) {
+            throw new RuntimeException('无可用用户创建订单，请先登录');
+        }
+
+        return $user;
+    }
+}

app/Blog/Services/MarketplaceClient.php

@@ -29,7 +29,16 @@ class MarketplaceClient
 
         $response->throw();
 
-        return $response->json('items', []);
+        $items = $response->json('items', []);
+
+        // 规范化市场契约：price 分、type（plugin/theme）、name
+        return array_map(function (array $item) {
+            $item['price'] = (int) ($item['price'] ?? 0);
+            $item['type'] = $item['type'] ?? 'plugin';
+            $item['name'] = $item['name'] ?? null;
+
+            return $item;
+        }, is_array($items) ? $items : []);
     }
 
     public function download(string $url): string