chore: improve ignore files and update ci badge

[AdekunleBamz]

This PR improves project hygiene and Docker build efficiency:

• CI Badge: Updated the CI status badge to point to the correct repository (AdekunleBamz/op-rbuilder) for accurate build status visibility.
• Gitignore: Added .DS_Store to prevent macOS system files from being committed.
• Docker Optimization: Significantly enhanced .dockerignore with comprehensive exclusion patterns:
  • Git metadata and CI files
  • Build artifacts (target/, cargo/, data/, test/, integration_logs/, benchmark results)
  • IDE/editor configurations
  • Documentation files
  • Development tools (justfile, Makefile, zepter.yaml, etc.)
  • Environment and test contract artifacts

This reduces Docker build context from ~162MB to less than 10MB, significantly speeding up image builds and reducing disk usage in containerized environments.