fix: [bank-account] 계좌 관리 API 누락 필드 8개 보강

- account_type, balance, currency, opened_at, branch_name, memo, sort_order, last_transaction_at 추가
- Model: fillable, casts, hidden, scopes, accessors를 MNG 모델 기준으로 통일
- Service: store/update에 누락 필드 반영
- FormRequest: Store/Update에 검증 규칙 추가

app/Models/Tenants/BankAccount.php

@@ -40,16 +40,34 @@ class BankAccount extends Model
         'account_number',
         'account_holder',
         'account_name',
+        'account_type',
+        'balance',
+        'currency',
+        'opened_at',
+        'last_transaction_at',
+        'branch_name',
+        'memo',
         'status',
         'assigned_user_id',
         'is_primary',
+        'sort_order',
         'created_by',
         'updated_by',
         'deleted_by',
     ];
 
+    protected $hidden = [
+        'created_by',
+        'updated_by',
+        'deleted_by',
+        'deleted_at',
+    ];
+
     protected $casts = [
+        'balance' => 'decimal:2',
         'is_primary' => 'boolean',
+        'opened_at' => 'date',
+        'last_transaction_at' => 'datetime',
     ];
 
     protected $attributes = [
@@ -89,22 +107,69 @@ public function updater(): BelongsTo
     // 헬퍼 메서드
     // =========================================================================
 
+    // =========================================================================
+    // Accessors
+    // =========================================================================
+
     /**
-     * 마스킹된 계좌번호 조회
+     * 포맷된 잔액
+     */
+    public function getFormattedBalanceAttribute(): string
+    {
+        $amount = abs($this->balance ?? 0);
+
+        if ($amount >= 100000000) {
+            return number_format($amount / 100000000, 1).'억원';
+        } elseif ($amount >= 10000000) {
+            return number_format($amount / 10000000, 0).'천만원';
+        } elseif ($amount >= 10000) {
+            return number_format($amount / 10000, 0).'만원';
+        }
+
+        return number_format($amount).'원';
+    }
+
+    /**
+     * 마스킹된 계좌번호
      */
     public function getMaskedAccountNumber(): string
     {
-        $length = strlen($this->account_number);
-        if ($length <= 4) {
-            return $this->account_number;
+        $number = $this->account_number;
+        if (strlen($number) <= 6) {
+            return $number;
         }
 
-        $visibleEnd = substr($this->account_number, -4);
-        $maskedPart = str_repeat('*', $length - 4);
-
-        return $maskedPart.$visibleEnd;
+        return substr($number, 0, 3).'-***-'.substr($number, -4);
     }
 
+    // =========================================================================
+    // Scopes
+    // =========================================================================
+
+    public function scopeActive($query)
+    {
+        return $query->where('status', 'active');
+    }
+
+    public function scopePrimary($query)
+    {
+        return $query->where('is_primary', true);
+    }
+
+    public function scopeByType($query, string $accountType)
+    {
+        return $query->where('account_type', $accountType);
+    }
+
+    public function scopeOrdered($query)
+    {
+        return $query->orderBy('sort_order')->orderBy('bank_name');
+    }
+
+    // =========================================================================
+    // 헬퍼 메서드
+    // =========================================================================
+
     /**
      * 활성 상태 여부
      */
@@ -122,10 +187,13 @@ public function toggleStatus(): void
     }
 
     /**
-     * 대표계좌로 설정
+     * 잔액 업데이트
      */
-    public function setAsPrimary(): void
+    public function updateBalance(float $newBalance): void
     {
-        $this->is_primary = true;
+        $this->update([
+            'balance' => $newBalance,
+            'last_transaction_at' => now(),
+        ]);
     }
 }