test(settings): add policy compiler sanitizer fixtures

[JSONbored]

Parent roadmap: #127
Parent phase: #236
Parent epic: #277
Related advanced phase: #269

Goal

Add sanitizer fixtures for policy compiler output before it feeds public onboarding or maintainer guidance.

Requirements

• Cover contribution lanes, label guidance, validation guidance, readiness warnings, and onboarding-pack inputs.
• Assert forbidden public text and sensitive fields are removed or fail closed.
• Keep fixtures focused so implementation PRs can extend them incrementally.

Acceptance criteria

• Public policy compiler output cannot leak private scoreability, private reviewability, reward estimates, wallet, hotkey, raw trust, or private maintainer context.
• Sanitizer tests cover both public and private/authenticated output paths.
• This is not public scoring or autonomous GitHub action.

Validation expected

• Targeted policy compiler sanitizer fixture tests.
• npm run test:ci.