feat(app): expose private recommendation quality report

[JSONbored]

Parent roadmap: #127
Parent phase: #237
Parent epic: #278
Related advanced phase: #269
Related base feedback issue: #96

Goal

Expose a private recommendation quality report so operators can see whether Gittensory guidance is getting better.

Requirements

• Show role-aware outcome quality, trends, and useful failure categories.
• Keep the report authenticated/private and avoid public GitHub output.
• Avoid reward claims, public score prediction, wallet, hotkey, raw trust, private scoreability, and private reviewability.

Acceptance criteria

• Operators can inspect recommendation quality without leaking private scoring context.
• The report separates miner, maintainer, repo-owner, and operator surfaces where data exists.
• Public exports or snippets are sanitized or unavailable by default.
• This is not an autonomous PR bot and not public scoring.

Validation expected

• UI/API tests for populated, empty, sparse, and private-field states.
• Screenshot or recording for changed UI state.
• npm run test:ci.