feat(scoring): simulate linked-issue and branch eligibility scenarios

[JSONbored]

Parent roadmap: #127
Parent phase: #269
Parent epic: #271

Goal

Model whether a candidate branch or PR is eligible enough to pursue based on linked issue state and branch signals.

Requirements

• Simulate linked-issue present/missing/closed/reopened cases.
• Include branch eligibility and current local branch signals where available.
• Keep local source upload fail-closed and avoid exposing local path/source context publicly.

Acceptance criteria

• Scenario output explains eligibility blockers and cleanup paths.
• Public summaries avoid private scoreability, reward/risk, wallet, hotkey, and trust context.
• The simulator does not recommend public action without human approval.
• This is not an autonomous PR bot and not public scoring.

Validation expected

• Fixtures for linked, unlinked, closed-link, and branch-ineligible cases.
• Public/private sanitizer tests.
• npm run test:ci.