Feat: 商店功能完整实现（单次特效卡888/周卡8888/改名卡5000，含购买、周卡覆盖、改名黑名单）

app/Models/UserPurchase.php

@@ -0,0 +1,57 @@
+<?php
+
+/**
+ * 文件功能：用户购买记录模型
+ * 对应 user_purchases 表，追踪每次商品购买的状态与有效期
+ */
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\BelongsTo;
+
+class UserPurchase extends Model
+{
+    protected $table = 'user_purchases';
+
+    protected $fillable = [
+        'user_id', 'shop_item_id', 'status', 'price_paid',
+        'expires_at', 'used_at',
+    ];
+
+    protected $casts = [
+        'expires_at' => 'datetime',
+        'used_at' => 'datetime',
+    ];
+
+    /**
+     * 购买记录所属用户
+     */
+    public function user(): BelongsTo
+    {
+        return $this->belongsTo(User::class);
+    }
+
+    /**
+     * 购买记录对应的商品
+     */
+    public function shopItem(): BelongsTo
+    {
+        return $this->belongsTo(ShopItem::class, 'shop_item_id');
+    }
+
+    /**
+     * 判断周卡是否仍在有效期内
+     */
+    public function isAlive(): bool
+    {
+        if ($this->status !== 'active') {
+            return false;
+        }
+        if ($this->expires_at && $this->expires_at->isPast()) {
+            return false;
+        }
+
+        return true;
+    }
+}