PR_26175_OWNER_050-project-instructions-add-valid-reference-files

[ToolboxAid]

Summary

• Adds Project Reference Files Governance for recognized instruction/reference documents.
• Recognizes Installs required.txt and Table layout.txt when present in ProjectInstructions.zip, the active instruction directory, or docs_build/dev/admin-notes/.
• Updates instruction indexes, release gate guidance, startup guidance, admin-note ownership, reports, and Codex review artifacts.

Validation

• PASS: git status --short --branch
• PASS: git rev-list --left-right --count origin/main...HEAD
• PASS: git diff --name-only
• PASS: git diff --check
• PASS: targeted rg reference checks
• PASS: canonical file presence checks

Runtime/UI changes: none.