feat: 添加SplitType枚举并在CommissionService中使用，以增强分账记录的可读性

app/Enums/SplitType.php

@@ -0,0 +1,11 @@
+<?php
+
+namespace App\Enums;
+
+enum SplitType: int
+{
+    case PlatformCommission = 1;
+    case AgentCommission = 2;
+    case CoachCommission = 3;
+    case InviterCommission = 4;
+}

app/Services/Coach/CommissionService.php

@@ -11,6 +11,7 @@ use App\Models\WalletSplitRecord;
 use Illuminate\Support\Facades\DB;
 use Illuminate\Support\Facades\Log;
 use App\Enums\StorageType;
+use App\Enums\SplitType;
 
 class CommissionService
 {
@@ -196,7 +197,7 @@ class CommissionService
         }
 
         // 记录平台分账
-        $this->createSplitRecord($order->id, 1, 'platform_commission', $baseAmount, $platformRate, $platformAmount, '平台分账');
+        $this->createSplitRecord($order->id, 1, SplitType::PlatformCommission->value, $baseAmount, $platformRate, $platformAmount, '平台分账');
     }
 
     /**