Add reedsolo to Docker, update docs for docker/ paths

- Add reedsolo>=1.7.0 to Dockerfile and Dockerfile.base for DCT
  error correction (fixes DCT decode failures in container)
- Update all documentation to use docker/docker-compose.yml paths

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

CLI.md

@@ -810,7 +810,7 @@ stegasoo decode -r ref.jpg -s stego.png -p "phrase" --pin 123456
 
 ### Docker Deployment
 
-**docker-compose.yml:**
+**docker/docker-compose.yml:**
 ```yaml
 x-common-env: &common-env
   STEGASOO_CHANNEL_KEY: ${STEGASOO_CHANNEL_KEY:-}