feat: add LLM review results panel to bounty detail

[alchip]

Summary

• add LLM Review Results panel on bounty detail page
• show Claude/Codex/Gemini scores side-by-side
• include quality badges + confidence percentages + review summary text
• add optional link to full reasoning when detail URL is available
• add API + hook layer for /api/bounties/:id/reviews with safe fallback

Why

Issue #837 requests a bounty detail view that surfaces multi-LLM review results and confidence clearly.

Acceptance mapping

• Display scores from all three LLMs side-by-side
• Show quality indicators and confidence percentages
• Link to full review details with reasoning (when provided)

Closes #837

Wallet

Wallet: 74jSPYaxEJcGEuW4jr6bqQdg2iuLChyLEuEmC8QhcQVW

[nagiexplorer88]

This is now mounted on the bounty detail page, but it still is not connected to a real review-results source.

listBountyReviews() calls /api/bounties/${bountyId}/reviews, but this PR does not add a backend route for that path, and I do not see an existing backend reviews/comments route in the repository. When the request fails, the catch block returns FALLBACK_REVIEWS with hard-coded Claude/Codex/Gemini scores, confidence percentages, and summaries.

That means a live bounty detail page can show plausible-looking LLM review results even when no actual Claude/Codex/Gemini review exists. For #837, the panel should either be backed by the real review-results API/details URL, or show an unavailable/empty state instead of fabricated scores when the API is missing.