feat: bind framework-native eval reports

[stackbilt-admin]

Summary

• add a public projection API for framework-native private reports
• hash native reports as-is while exposing only standard aggregate fields
• document and test private-field exclusion and digest binding
• bump @stackbilt/evals to 0.2.1

Verification

• npm test (11 tests)
• npm run build
• git diff --check