feat: 웹사이트 표준화 검사 도구 구현

- 4개 검사 엔진: HTML/CSS, 접근성(WCAG), SEO, 성능/보안 (총 50개 항목)
- FastAPI 백엔드 (9개 API, SSE 실시간 진행, PDF/JSON 리포트)
- Next.js 15 프론트엔드 (6개 페이지, 29개 컴포넌트, 반원 게이지 차트)
- Docker Compose 배포 (Backend:8011, Frontend:3011, MongoDB:27022, Redis:6392)
- 전체 테스트 32/32 PASS

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

backend/app/core/redis.py

@@ -0,0 +1,110 @@
+"""
+Redis connection management using redis-py async client.
+"""
+
+import json
+import logging
+from redis.asyncio import Redis
+from app.core.config import get_settings
+
+logger = logging.getLogger(__name__)
+
+_redis: Redis | None = None
+
+
+async def connect_redis() -> None:
+    """Establish Redis connection."""
+    global _redis
+    settings = get_settings()
+    _redis = Redis.from_url(
+        settings.REDIS_URL,
+        decode_responses=True,
+    )
+    # Verify connection
+    await _redis.ping()
+    logger.info("Redis connected successfully: %s", settings.REDIS_URL)
+
+
+async def close_redis() -> None:
+    """Close Redis connection."""
+    global _redis
+    if _redis is not None:
+        await _redis.close()
+        _redis = None
+        logger.info("Redis connection closed")
+
+
+def get_redis() -> Redis:
+    """Get Redis instance."""
+    if _redis is None:
+        raise RuntimeError("Redis is not connected. Call connect_redis() first.")
+    return _redis
+
+
+# --- Helper functions ---
+
+PROGRESS_TTL = 300  # 5 minutes
+RESULT_CACHE_TTL = 3600  # 1 hour
+RECENT_LIST_TTL = 300  # 5 minutes
+
+
+async def set_inspection_status(inspection_id: str, status: str) -> None:
+    """Set inspection status in Redis with TTL."""
+    r = get_redis()
+    key = f"inspection:{inspection_id}:status"
+    await r.set(key, status, ex=PROGRESS_TTL)
+
+
+async def get_inspection_status(inspection_id: str) -> str | None:
+    """Get inspection status from Redis."""
+    r = get_redis()
+    key = f"inspection:{inspection_id}:status"
+    return await r.get(key)
+
+
+async def update_category_progress(
+    inspection_id: str, category: str, progress: int, current_step: str
+) -> None:
+    """Update category progress in Redis hash."""
+    r = get_redis()
+    key = f"inspection:{inspection_id}:progress"
+    await r.hset(key, mapping={
+        f"{category}_progress": str(progress),
+        f"{category}_step": current_step,
+        f"{category}_status": "completed" if progress >= 100 else "running",
+    })
+    await r.expire(key, PROGRESS_TTL)
+
+
+async def get_current_progress(inspection_id: str) -> dict | None:
+    """Get current progress data from Redis."""
+    r = get_redis()
+    key = f"inspection:{inspection_id}:progress"
+    data = await r.hgetall(key)
+    if not data:
+        return None
+    return data
+
+
+async def publish_event(inspection_id: str, event_data: dict) -> None:
+    """Publish an SSE event via Redis Pub/Sub."""
+    r = get_redis()
+    channel = f"inspection:{inspection_id}:events"
+    await r.publish(channel, json.dumps(event_data, ensure_ascii=False))
+
+
+async def cache_result(inspection_id: str, result: dict) -> None:
+    """Cache inspection result in Redis."""
+    r = get_redis()
+    key = f"inspection:result:{inspection_id}"
+    await r.set(key, json.dumps(result, ensure_ascii=False, default=str), ex=RESULT_CACHE_TTL)
+
+
+async def get_cached_result(inspection_id: str) -> dict | None:
+    """Get cached inspection result from Redis."""
+    r = get_redis()
+    key = f"inspection:result:{inspection_id}"
+    data = await r.get(key)
+    if data:
+        return json.loads(data)
+    return None