feat: 세금 시뮬레이션 API 개발 (Phase 1.3)

- LoanService에 taxSimulation() 메서드 추가
- LoanController에 taxSimulation() 액션 추가
- GET /api/v1/loans/tax-simulation 라우트 등록
- Swagger LoanTaxSimulation 스키마 및 엔드포인트 문서화
- 법인세/소득세 비교 분석 데이터 제공

Co-Authored-By: Claude <noreply@anthropic.com>

routes/api.php

@@ -563,6 +563,7 @@
             Route::get('', [ExpectedExpenseController::class, 'index'])->name('v1.expected-expenses.index');
             Route::post('', [ExpectedExpenseController::class, 'store'])->name('v1.expected-expenses.store');
             Route::get('/summary', [ExpectedExpenseController::class, 'summary'])->name('v1.expected-expenses.summary');
+            Route::get('/dashboard-detail', [ExpectedExpenseController::class, 'dashboardDetail'])->name('v1.expected-expenses.dashboard-detail');
             Route::delete('', [ExpectedExpenseController::class, 'destroyMany'])->name('v1.expected-expenses.destroy-many');
             Route::put('/update-payment-date', [ExpectedExpenseController::class, 'updateExpectedPaymentDate'])->name('v1.expected-expenses.update-payment-date');
             Route::get('/{id}', [ExpectedExpenseController::class, 'show'])->whereNumber('id')->name('v1.expected-expenses.show');
@@ -576,6 +577,7 @@
             Route::post('', [LoanController::class, 'store'])->name('v1.loans.store');
             Route::get('/summary', [LoanController::class, 'summary'])->name('v1.loans.summary');
             Route::get('/dashboard', [LoanController::class, 'dashboard'])->name('v1.loans.dashboard');
+            Route::get('/tax-simulation', [LoanController::class, 'taxSimulation'])->name('v1.loans.tax-simulation');
             Route::post('/calculate-interest', [LoanController::class, 'calculateInterest'])->name('v1.loans.calculate-interest');
             Route::get('/interest-report/{year}', [LoanController::class, 'interestReport'])->whereNumber('year')->name('v1.loans.interest-report');
             Route::get('/{id}', [LoanController::class, 'show'])->whereNumber('id')->name('v1.loans.show');