Publish Docker image to GHCR + MCP Registry

[francomano]

Problem

CoreBall now has a zero-deps MCP server and HTTP API, but discovery is manual. The fastest growth channel in 2025-2026 is the MCP Registry + Docker pull for Claude Desktop / Cursor.

Proposal

• Dockerfile (python:3.11-slim, coreball mcp as ENTRYPOINT, coreball serve via --api flag)
• GitHub workflow to publish ghcr.io/francomano/coreball:latest + version tag
• mcp-registry.json manifest + PR to https://github.com/modelcontextprotocol/registry
• Add docker pull badge and MCP Registry badge to README

Benefits

• One-command install for Claude Desktop, Cursor, Windsurf: docker run ghcr.io/francomano/coreball mcp
• Algorthm boost: docker, mcp, ghcr are top GitHub search terms — registry listing drives stars/PRs.
• Zero runtime deps preserved (image stays <80MB).

Acceptance criteria

• Dockerfile builds locally and MCP smoke passes (printf '...' | docker run ...)
• GH workflow publishes on tag + on main
• Registry PR merged (or filed)
• Docs updated with docker run examples

Good first issue for someone who likes Docker + MCP.