feat: 보고서(Reports) API 구현

- 일일 일보 조회/엑셀 다운로드 API 추가
- 지출 예상 내역서 조회/엑셀 다운로드 API 추가
- ReportService: 전일/당일 잔액 계산, 월별 지출 예상 집계
- Laravel Excel을 이용한 엑셀 내보내기 구현
- Swagger 문서 작성 완료

app/Http/Requests/V1/Report/DailyReportRequest.php

@@ -0,0 +1,36 @@
+<?php
+
+namespace App\Http\Requests\V1\Report;
+
+use Illuminate\Foundation\Http\FormRequest;
+
+class DailyReportRequest extends FormRequest
+{
+    /**
+     * Determine if the user is authorized to make this request.
+     */
+    public function authorize(): bool
+    {
+        return true;
+    }
+
+    /**
+     * Get the validation rules that apply to the request.
+     */
+    public function rules(): array
+    {
+        return [
+            'date' => ['nullable', 'date', 'date_format:Y-m-d'],
+        ];
+    }
+
+    /**
+     * Custom attribute names
+     */
+    public function attributes(): array
+    {
+        return [
+            'date' => __('validation.attributes.date'),
+        ];
+    }
+}

app/Http/Requests/V1/Report/ExpenseEstimateRequest.php

@@ -0,0 +1,46 @@
+<?php
+
+namespace App\Http\Requests\V1\Report;
+
+use Illuminate\Foundation\Http\FormRequest;
+
+class ExpenseEstimateRequest extends FormRequest
+{
+    /**
+     * Determine if the user is authorized to make this request.
+     */
+    public function authorize(): bool
+    {
+        return true;
+    }
+
+    /**
+     * Get the validation rules that apply to the request.
+     */
+    public function rules(): array
+    {
+        return [
+            'year_month' => ['nullable', 'regex:/^\d{4}-\d{2}$/'],
+        ];
+    }
+
+    /**
+     * Custom attribute names
+     */
+    public function attributes(): array
+    {
+        return [
+            'year_month' => __('validation.attributes.year_month'),
+        ];
+    }
+
+    /**
+     * Custom validation messages
+     */
+    public function messages(): array
+    {
+        return [
+            'year_month.regex' => __('validation.date_format', ['format' => 'YYYY-MM']),
+        ];
+    }
+}