feat(customers): tambahkan model dan migrasi untuk tabel customers

- Menambahkan model Customer dengan relasi ke akun dan cabang.
- Membuat migrasi untuk tabel customers dengan kolom yang diperlukan.

database/migrations/2025_02_06_072406_create_customers_table.php

@@ -0,0 +1,33 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    /**
+     * Run the migrations.
+     */
+    public function up(): void
+    {
+        Schema::create('customers', function (Blueprint $table) {
+            $table->id();
+            $table->string('customer_code')->unique();
+            $table->string('name')->nullable();
+            $table->text('address')->nullable();
+            $table->string('branch_code')->nullable();
+            $table->string('date_of_birth')->nullable();
+            $table->string('email')->nullable();
+            $table->timestamps();
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     */
+    public function down(): void
+    {
+        Schema::dropIfExists('customers');
+    }
+};