Frontend routes — Project admin workspace

[Circuit-Overtime]

Parent: #6

Build repository-scoped operations for project admins and maintainers.

Routes

• /manage/[contestId]/projects/[repositoryId] — project overview
• /manage/[contestId]/projects/[repositoryId]/issues — issue operations
• /manage/[contestId]/projects/[repositoryId]/submissions — PR verification queue
• /manage/[contestId]/projects/[repositoryId]/labels — label rule mapping
• /manage/[contestId]/projects/[repositoryId]/contributors — project participants

Acceptance criteria

• Repository scope remains visible on every route
• Bulk and verification actions require confirmation and reason where relevant
• Permission, stale-data, empty, and failure states are included
• No backend implementation is included