feat: [finance] 계정과목 및 일반전표 API 추가

- AccountCode 모델/서비스/컨트롤러 구현
- JournalEntry, JournalEntryLine 모델 구현
- GeneralJournalEntry 서비스/컨트롤러 구현
- FormRequest 검증 클래스 추가
- finance 라우트 등록
- i18n 메시지 키 추가 (message.php, error.php)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/Http/Controllers/Api/V1/GeneralJournalEntryController.php

@@ -0,0 +1,85 @@
+<?php
+
+namespace App\Http\Controllers\Api\V1;
+
+use App\Helpers\ApiResponse;
+use App\Http\Controllers\Controller;
+use App\Http\Requests\V1\GeneralJournalEntry\StoreManualJournalRequest;
+use App\Http\Requests\V1\GeneralJournalEntry\UpdateJournalRequest;
+use App\Services\GeneralJournalEntryService;
+use Illuminate\Http\Request;
+
+class GeneralJournalEntryController extends Controller
+{
+    public function __construct(
+        private readonly GeneralJournalEntryService $service
+    ) {}
+
+    /**
+     * 일반전표 통합 목록 조회
+     */
+    public function index(Request $request)
+    {
+        $params = $request->only([
+            'start_date', 'end_date', 'search', 'page', 'per_page',
+        ]);
+
+        $result = $this->service->index($params);
+
+        return ApiResponse::success($result, __('message.fetched'));
+    }
+
+    /**
+     * 요약 통계
+     */
+    public function summary(Request $request)
+    {
+        $params = $request->only([
+            'start_date', 'end_date', 'search',
+        ]);
+
+        $summary = $this->service->summary($params);
+
+        return ApiResponse::success($summary, __('message.fetched'));
+    }
+
+    /**
+     * 수기전표 등록
+     */
+    public function store(StoreManualJournalRequest $request)
+    {
+        $entry = $this->service->store($request->validated());
+
+        return ApiResponse::success($entry, __('message.created'), [], 201);
+    }
+
+    /**
+     * 전표 상세 조회 (분개 수정 모달용)
+     */
+    public function show(int $id)
+    {
+        $detail = $this->service->show($id);
+
+        return ApiResponse::success($detail, __('message.fetched'));
+    }
+
+    /**
+     * 분개 수정
+     */
+    public function updateJournal(int $id, UpdateJournalRequest $request)
+    {
+        $entry = $this->service->updateJournal($id, $request->validated());
+
+        return ApiResponse::success($entry, __('message.updated'));
+    }
+
+    /**
+     * 분개 삭제
+     */
+    public function destroyJournal(int $id)
+    {
+        $this->service->destroyJournal($id);
+
+        return ApiResponse::success(null, __('message.deleted'));
+    }
+}