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/ShopItem.php

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+<?php
+
+/**
+ * 文件功能：商店商品模型
+ * 对应 shop_items 表，存储商品定义信息
+ */
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Collection;
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\HasMany;
+
+class ShopItem extends Model
+{
+    protected $table = 'shop_items';
+
+    protected $fillable = [
+        'name', 'slug', 'description', 'icon', 'price',
+        'type', 'duration_days', 'sort_order', 'is_active',
+    ];
+
+    protected $casts = [
+        'is_active' => 'boolean',
+    ];
+
+    /**
+     * 获取该商品的所有购买记录
+     */
+    public function purchases(): HasMany
+    {
+        return $this->hasMany(UserPurchase::class);
+    }
+
+    /**
+     * 是否为特效类商品（instant 或 duration，slug 以 once_ 或 week_ 开头）
+     */
+    public function isEffect(): bool
+    {
+        return str_starts_with($this->slug, 'once_') || str_starts_with($this->slug, 'week_');
+    }
+
+    /**
+     * 是否为周卡（duration 类型）
+     */
+    public function isWeekCard(): bool
+    {
+        return $this->type === 'duration';
+    }
+
+    /**
+     * 是否为单次卡（instant 类型）
+     */
+    public function isInstant(): bool
+    {
+        return $this->type === 'instant';
+    }
+
+    /**
+     * 获取特效 key（去掉 once_ / week_ 前缀，返回 fireworks/rain/lightning/snow）
+     */
+    public function effectKey(): ?string
+    {
+        if (str_starts_with($this->slug, 'once_')) {
+            return substr($this->slug, 5);
+        }
+        if (str_starts_with($this->slug, 'week_')) {
+            return substr($this->slug, 5);
+        }
+
+        return null;
+    }
+
+    /**
+     * 获取所有上架商品（按排序）
+     */
+    public static function active(): Collection
+    {
+        return static::where('is_active', true)->orderBy('sort_order')->get();
+    }
+}

app/Models/UserPurchase.php

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+<?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;
+    }
+}

app/Models/UsernameBlacklist.php

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+<?php
+
+/**
+ * 文件功能：用户名黑名单模型
+ * 用户改名后旧名称写入此表，保留期间其他人无法注册该名称
+ */
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Model;
+
+class UsernameBlacklist extends Model
+{
+    protected $table = 'username_blacklist';
+
+    public $timestamps = false; // 只有 created_at 无 updated_at
+
+    protected $fillable = ['username', 'reserved_until', 'created_at'];
+
+    protected $casts = [
+        'reserved_until' => 'datetime',
+        'created_at' => 'datetime',
+    ];
+
+    /**
+     * 判断给定名称是否在黑名单有效期内
+     */
+    public static function isReserved(string $username): bool
+    {
+        return static::where('username', $username)
+            ->where('reserved_until', '>', now())
+            ->exists();
+    }
+}