Audit public documentation readiness

[JuanTorchia]

Summary

• Add a reusable local Markdown link checker for public repository documentation.
• Record the public documentation audit in the engineering log and index it.
• Remove workstation-specific verification details from the historical public-readiness log and ignore Python bytecode artifacts.

Validation

• python -B scripts/check-local-markdown-links.py
• python -m py_compile scripts/check-local-markdown-links.py
• Legacy documentation path search returns only the historical rename note in docs/engineering-log/012-public-repository-readiness.md.
• Public documentation hygiene search returns no workstation-specific paths or private planning references.
• mvn clean test '-Dmaven.compiler.release=22'

Closes #3.