chore: prepare rubric_llm 0.4.1 release

[dpaluy]

Summary

• Bump rubric_llm from 0.4.0 to 0.4.1.
• Record the patch release in CHANGELOG.md.
• Add the resolved Gemfile.lock for reproducible release verification.

Verification

• mise exec ruby@3.4.5 -- bundle exec rake test — 141 runs, 328 assertions, 0 failures, 0 errors, 0 skips.
• mise exec ruby@3.4.5 -- bundle exec rubocop — 45 files inspected, no offenses.
• mise exec ruby@4.0.5 -- bundle exec rake test — 141 runs, 328 assertions, 0 failures, 0 errors, 0 skips.
• mise exec ruby@4.0.5 -- bundle exec rubocop — 45 files inspected, no offenses.
• mise exec ruby@3.4.5 -- bundle exec rake build — rubric_llm 0.4.1 built successfully.

No tag or RubyGems publish is included; release publication remains with the existing workflow.