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/config.py

@@ -0,0 +1,34 @@
+"""
+Application configuration from environment variables.
+"""
+
+from pydantic_settings import BaseSettings
+from functools import lru_cache
+
+
+class Settings(BaseSettings):
+    """Application settings loaded from environment variables."""
+
+    # MongoDB
+    MONGODB_URL: str = "mongodb://admin:password123@localhost:27022/"
+    DB_NAME: str = "web_inspector"
+
+    # Redis
+    REDIS_URL: str = "redis://localhost:6392"
+
+    # Inspection
+    URL_FETCH_TIMEOUT: int = 10
+    CATEGORY_TIMEOUT: int = 60
+    MAX_HTML_SIZE: int = 10485760  # 10MB
+
+    # Application
+    PROJECT_NAME: str = "Web Inspector API"
+
+    class Config:
+        env_file = ".env"
+        case_sensitive = True
+
+
+@lru_cache()
+def get_settings() -> Settings:
+    return Settings()