The win probability sparkline component is now fully integrated:
1. Worker (engine/winprob.go): Monte Carlo rollout computes per-turn win
probabilities, detectCriticalMoments identifies turns where win prob
shifts >15% with template-based descriptions.
2. Replay storage (engine/replay.go): win_prob and critical_moments arrays
stored in replay JSON, written by match worker after each match.
3. Web component (web/src/components/win-prob.ts): WinProbSparkline class
renders the graph with critical moment markers (dashed vertical lines),
click-to-scrub interaction, and current turn indicator.
4. Replay page integration (web/src/pages/replay.ts): initWinProb() sets up
the sparkline with player colors, legend, prev/next critical moment
navigation buttons, and keyboard shortcuts ([/]).
The sparkline displays one line per player with area fill gradient,
percentage labels (0%, 50%, 100%), critical moment diamonds with
delta labels, and updates in real-time as the replay plays.
c66dc893fa