feat(agent): expose recommendation changes and rerun reasons in miner dashboard

[JSONbored]

Parent phase: #234
Parent roadmap: #127

Problem

Miners need to understand why Gittensory changed a recommendation after a rerun: upstream queue pressure, changed PR state, issue quality, repo policy, validation status, or stale context.

Acceptance criteria

• Recommendation cards include changed-since-last-run signals with evidence labels.
• Rerun reasons are grouped by repo state, contributor state, validation state, and policy/context state.
• Private scoreability remains private and is never copied into public PR text.

Validation expected

• Unit tests cover deterministic rerun reason construction.
• UI evidence shows changed and unchanged recommendation states.

UI evidence gate

Any visible web, browser-extension, or GitHub-overlay change must include maintainer-reviewable screenshots or a short recording covering the changed states. A checked template box without actual visual evidence is not enough.

Public-output safety criteria

• Public text is sanitized before reaching GitHub comments, issue bodies, PR bodies, extension-visible public panels, or copied public snippets.
• Tests cover forbidden wallet/hotkey, reward-estimate, trust-score, public-score-prediction, private-reviewability, private-scoreability, and farming-language leakage.

Cross-cutting acceptance criteria

• Preserve the repo quality gate: npm run test:ci, 97%+ global coverage, and the local branch coverage target for touched code.
• Keep public/private boundaries explicit. Public GitHub output must not expose wallets, hotkeys, reward estimates, raw trust scores, public score predictions, private reviewability, private scoreability context, or farming language.
• Add/update focused tests for the changed behavior instead of relying on green checks alone.