fix(package-detection): verify Docker compare targets

[mstykow]

Summary

• verify the four Docker compare targets in the scorecard (moby/moby, docker-library/official-images, docker-library/python, and getsentry/self-hosted) and record their final benchmark rows
• recover structured Maintainers ... author lines during shared author detection, trimming Docker-library GitRepo trailers without adding target-specific tuning
• mark the Docker row verified and clarify in the scorecard methodology that --profile common verification covers shared license, copyright, author, email, and URL detection as well as parser behavior

Scope and exclusions

• Included:
  • focused author-detection heuristic and unit coverage for Docker-library maintainer lines
  • final compare-output reruns for all four Docker repositories on this branch state
  • docs/BENCHMARKS.md and scorecard updates for the verified Docker lane
• Explicit exclusions:
  • no new parser surface beyond the existing Dockerfile verification lane
  • no golden or parser expected-output fixture updates

Follow-up work

• Created or intentionally deferred:
  • none

Expected-output fixture changes

• Files changed: none
• Why the new expected output is correct: the maintainer-line change is covered by focused detector tests plus the saved compare artifacts, so no .expected.json or golden YAML snapshot needed updating.