fix: clean up Docker files after merge

[aborruso]

Hi @piersoft, thanks for the Docker support contribution! 🐳

After merging #14, I'll apply a few cleanup changes to align the files with the project conventions:

• Translate all comments to English — Dockerfile, docker-compose.yml, and ckan-mcp-bridge.js contain Italian comments; the project uses English throughout
• Remove unused portals.json COPY line in Dockerfile — the file doesn't exist in the repo
• Fix .dockerignore reference in DOCKER-README.md — it's mentioned as a required file but wasn't included in the PR

No functional changes — only cosmetic and consistency fixes.

[aborruso]

Done in 92b264e. Translated all comments to English, removed unused portals.json COPY line, moved bridge script and docs to docker/.