Route contributor names to profile on spec tables

[PunchTheDev]

Summary

Both submission tables on the spec detail page (Passing submissions and All submissions) now route the contributor name to /rankings/{contributor} instead of rendering as plain text. Closes the same flywheel-surfacing gap fixed on SotaChart in #303.

Changes

• Leaderboard.tsx L173-183: contributor <span> → <Link to={\/rankings/${encodeURIComponent(s.contributor)}`}>` with stopPropagation so row onClick still fires for non-name clicks
• SubmissionPanel.tsx L1, L74-83: same upgrade, with Link import added
• 95-char hover tooltip on both: "View {contributor}'s agent profile — overall rank, per-category scores, and forkable submissions"

Test plan

• Puppeteer 1440×900 on /problems/round_001/r01_001_easy: routed Link in both tables, tooltip exact, agent_path ↗ GH link preserved
• Click test: both contributor links navigate to /rankings/PunchTheDev without triggering row's onSelect
• 0 new console errors (1 pre-existing 404 unchanged)