The ts-cleaner step in the build script scans dist/ and crashes with
ENOENT if the directory doesn't exist (e.g. on a fresh clone or after
git clean). Previously README told users to 'mkdir -p dist' first,
but Dockerfile and CI didn't necessarily follow that. Prepend a small
node one-liner that mkdir's dist recursively before ts-cleaner runs,
and drop the now-redundant manual step from README.
- Drop the 'known build defect' callout — tsconfig now compiles
cleanly with rootDir + ignoreDeprecations applied.
- Add SIGNATURE_HOST to the env var table.
코드베이스 분석 결과를 반영해 README를 placeholder에서 실사용 가능한 문서로 개편.
주요 기능, 슬래시/prefix 명령어, 기술 스택, 디렉터리 구조, 환경변수 표,
실행/Docker 절차, 동작 흐름을 정리하고, 현재 tsconfig 결함으로 인한
빌드 실패(TS5101/TS5011)와 해결 방법을 명시.
