✨ feat(balance): implementasi service layer untuk balance management

- Menambahkan `AccountBalanceService` dengan transaksi PostgreSQL dan proper error handling.
- Implementasi `BalanceServiceProvider` untuk mendukung dependency injection pattern.
- Registrasi `BalanceServiceProvider` dalam `WebstatementServiceProvider`.
- Penambahan `CAST` ke `DECIMAL(15,2)` untuk kompatibilitas PostgreSQL.
- Perhitungan balance summary mencakup opening balance dan closing balance.
- Agregasi transaksi dengan type casting yang aman.
- Implementasi database transaction handling dengan mekanisme rollback dan commit.
- Logging komprehensif untuk debugging dan audit trail.
- Mendukung balance inquiry berdasarkan tanggal maupun periode tertentu.
- Validasi akun dengan pengecekan `exists` untuk memastikan data valid.

app/Providers/BalanceServiceProvider.php

@@ -0,0 +1,31 @@
+<?php
+
+namespace Modules\Webstatement\Providers;
+
+use Illuminate\Support\ServiceProvider;
+use Modules\Webstatement\Services\AccountBalanceService;
+
+class BalanceServiceProvider extends ServiceProvider
+{
+    /**
+     * Register the service provider.
+     *
+     * @return void
+     */
+    public function register(): void
+    {
+        $this->app->singleton(AccountBalanceService::class, function ($app) {
+            return new AccountBalanceService();
+        });
+    }
+
+    /**
+     * Get the services provided by the provider.
+     *
+     * @return array<string>
+     */
+    public function provides(): array
+    {
+        return [AccountBalanceService::class];
+    }
+}

app/Providers/WebstatementServiceProvider.php

@@ -57,6 +57,7 @@ class WebstatementServiceProvider extends ServiceProvider
     {
         $this->app->register(EventServiceProvider::class);
         $this->app->register(RouteServiceProvider::class);
+        $this->app->register(BalanceServiceProvider::class);
         $this->app->bind(UpdateAtmCardBranchCurrencyJob::class);
     }