Frontend routes — Contributor dashboard and issue discovery

[Circuit-Overtime]

Parent: #6

Build the contributor experience for discovering work and tracking progress.

Routes

• /dashboard — contributor overview
• /dashboard/contests — joined contests
• /dashboard/claims — claimed issues
• /dashboard/contributions — PR and review history
• /dashboard/points — points ledger
• /dashboard/rewards — reward status
• /issues — cross-contest issue discovery
• /issues/[owner]/[repo]/[number] — issue details and claim state

Requirements

• URL-backed difficulty, language, repository, label, and contest filters
• Claim deadline, linked PR, verification, points, and reward states
• Responsive list, table, and card presentations
• Empty, loading, failure, and permission states

Acceptance criteria

• Every route is reachable from the contributor shell
• Filtered views are shareable by URL
• UI never implies a mutation succeeded before backend confirmation
• No backend implementation is included