fix: COPY PROJECT_README.md as README.md for hatchling

Dockerfile

@@ -9,8 +9,9 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
 
 RUN pip install --no-cache-dir uv
 
-# 소스 복사 (LICENSE + README — hatchling 빌드 필수)
-COPY pyproject.toml uv.lock LICENSE README.md ./
+# 소스 복사 (LICENSE + PROJECT_README — hatchling 빌드 필수)
+COPY pyproject.toml uv.lock LICENSE ./
+COPY PROJECT_README.md README.md
 COPY src/ src/
 
 # 설치