feat: migrate backend logging from Winston to Pino with correlation IDs (refs #82)

- Replace Winston with Pino using API-compatible wrapper
- Add LOG_LEVEL env var support with validation and fallback
- Add correlation ID middleware (X-Request-Id from Traefik or UUID)
- Configure PostgreSQL logging env vars (POSTGRES_LOG_STATEMENT, POSTGRES_LOG_MIN_DURATION)
- Configure Redis loglevel via command args

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

docker-compose.yml

@@ -218,6 +218,8 @@ services:
       POSTGRES_USER: postgres
       POSTGRES_PASSWORD_FILE: /run/secrets/postgres-password
       POSTGRES_INITDB_ARGS: --encoding=UTF8
+      POSTGRES_LOG_STATEMENT: ${POSTGRES_LOG_STATEMENT:-ddl}
+      POSTGRES_LOG_MIN_DURATION_STATEMENT: ${POSTGRES_LOG_MIN_DURATION:-500}
     volumes:
       - mvp_postgres_data:/var/lib/postgresql/data
       # Secrets (K8s Secrets equivalent)
@@ -243,7 +245,7 @@ services:
     image: ${REGISTRY_MIRRORS:-git.motovaultpro.com/egullickson/mirrors}/redis:8.4-alpine
     container_name: mvp-redis
     restart: unless-stopped
-    command: redis-server --appendonly yes
+    command: redis-server --appendonly yes --loglevel ${REDIS_LOGLEVEL:-notice}
     volumes:
       - mvp_redis_data:/data
     networks: