feat: 添加新的错误码以支持投注功能，更新数据库填充器以增强玩法和赔率配置，扩展 API 路由以支持风险池管理

app/Models/RiskPool.php

@@ -0,0 +1,37 @@
+<?php
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\BelongsTo;
+
+/** 赔付池事实表 {@see risk_pools} */
+class RiskPool extends Model
+{
+    protected $fillable = [
+        'draw_id',
+        'normalized_number',
+        'total_cap_amount',
+        'locked_amount',
+        'remaining_amount',
+        'sold_out_status',
+        'version',
+    ];
+
+    protected function casts(): array
+    {
+        return [
+            'draw_id' => 'integer',
+            'total_cap_amount' => 'integer',
+            'locked_amount' => 'integer',
+            'remaining_amount' => 'integer',
+            'sold_out_status' => 'integer',
+            'version' => 'integer',
+        ];
+    }
+
+    public function draw(): BelongsTo
+    {
+        return $this->belongsTo(Draw::class);
+    }
+}