fix(insta-render): F6 ReliableQueue 적용 — BLMOVE + ack/fail (F6 part 2)

- worker.py: BLPOP → ReliableQueue.dequeue / ack / fail / startup recovery
- _process_one: 예외 시 webhook(failed) 후 raise — poll_once가 fail(raw, payload)
  로 retry/dead-letter 처리
- poll_once 함수 추가 (테스트 단위)
- Dockerfile: build context=services/ 로 올리고 _shared 포함, PYTHONPATH=/app
- docker-compose.yml: insta-render build context 갱신

기존 webhook 호출 동작은 그대로 (멱등) — retry 시 매번 NAS에 failed 통보되어도
마지막 상태만 보임. dead-letter는 운영 모니터링으로 별도 처리.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

services/insta-render/Dockerfile

@@ -12,11 +12,14 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
     libcairo2 libasound2 libatspi2.0-0 \
  && rm -rf /var/lib/apt/lists/*
 
-COPY requirements.txt .
+COPY insta-render/requirements.txt /app/
 RUN pip install --no-cache-dir --timeout 600 --retries 5 -r requirements.txt
 RUN playwright install chromium
 
-COPY . .
+# F6: 공통 ReliableQueue 모듈 (services/_shared)
+COPY _shared /app/_shared
+COPY insta-render/. /app/
+ENV PYTHONPATH=/app
 
 EXPOSE 8000
 CMD ["python", "-m", "uvicorn", "main:app", "--host", "0.0.0.0", "--port", "8000", "--workers", "1"]