[#1] [ BOUNTY] Add diagnostic redaction regression tests

[lushan888]

Summary

Add deterministic tests that validate diagnostic redaction, artifact pairing, and repository-relative path reporting without relying on live services.

Changes

• tools/test_diagnostic_redaction.py: 6 hand-written tests
  • Metadata artifact paths are repo-relative / paths
  • No local home/temp/repo paths leaked in JSON or .logd
  • JSON and .logd are paired by commit ID
  • All required JSON fields present
  • Module artifact paths are repo-relative
  • Encryptly password is reasonable length
• All tests pass deterministically on Unix-like hosts

Testing

• 6/6 tests pass
• Tests work with existing diagnostic/build-00000000.json and generated artifacts
• No live service dependencies

Checklist

• Relevant modules affected by these changes build locally
• Tests pass locally
• Diagnostic build log is committed in this PR
• Documentation has been updated, if applicable
• Configuration or schema changes are documented, if applicable
• No generated build artifacts are committed, except the required diagnostic build log
• Changes are scoped to the PR purpose and avoid unrelated cleanup
• Security, privacy, and error-handling implications have been considered

Closes #1