chore: .gitignore에 logs/ 추가 및 application-dev.yml chunk 설정

- .gitignore: logs/ 디렉토리 제외 (개별 로그 파일 → 디렉토리 단위)
- application-dev.yml: chunk-size, sub-chunk-size 설정 추가

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.gitignore

@@ -71,3 +71,4 @@ application-local.yml
 frontend/node/
 frontend/node_modules/
 src/main/resources/static/
+logs/

src/main/resources/application-dev.yml

@@ -103,6 +103,8 @@ logging:
 # Custom Application Properties
 app:
   batch:
+    chunk-size: 10000
+    sub-chunk-size: 5000  # Writer Sub-Chunk 분할 크기
     api:
       url: https://api.example.com/data
       timeout: 30000