docs: add Actions quota hygiene convention

[haasonsaas]

Summary

• document EvalOps CodeQL PR scoping policy
• document artifact retention expectations
• document when diagnostic uploads should be best-effort

Test plan

• git diff --check

[cursor]

PR Summary

Low Risk
Low risk documentation-only change that does not modify CI behavior directly, but may influence how workflows are configured going forward.

Overview
Adds a new profile/GITHUB_ACTIONS_QUOTA.md convention documenting GitHub Actions quota hygiene: recommended CodeQL PR paths scoping, required artifact retention-days (and best-effort diagnostic uploads via continue-on-error), plus guidance on runner selection and documenting ubuntu-latest dependencies.

Updates profile/README.md to link this new operating convention.

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