feat(web): polish assistant release readiness

[KevinBigham]

Summary

• Polishes Mack Mercer with expression avatar hooks, shorter first-session cues, story-so-far context, and copyable playtest feedback.
• Expands OVR/rating visibility across profile, roster decisions, trade, finance, scouting, and minors surfaces.
• Hardens mobile Assistant/toast/nav behavior and accessibility basics for 390x844 closed-playtest smoke.

Save schema impact

None.

How to test

• npx --yes pnpm@9.15.4 --filter @mbd/web typecheck
• npx --yes pnpm@9.15.4 --filter @mbd/web test -- src/features/assistant src/app/routes/index.test.tsx src/app/layout/AppLayout.test.tsx src/app/App.test.tsx src/shared/components/RatingBadge.test.tsx
• npx --yes pnpm@9.15.4 --filter @mbd/web test -- src/workers/sim.worker.test.ts
• npx --yes pnpm@9.15.4 --filter @mbd/web build
• npx --yes pnpm@9.15.4 --filter @mbd/contracts test
• npx --yes pnpm@9.15.4 run verify:determinism
• Production preview at 390x844: Setup, Dashboard, Roster, Player Profile, Draft, Trade, Scouting, Finance, Free Agency, Settings, mobile bottom tabs, update toast, Assistant feedback form.

Risks / handoff for Claude Code

• Stacked on PR Add Mack Mercer route-aware tutorial assistant #72; merge after goal/tutorial-assistant-v1 lands or retarget if needed.
• Incoming AI-generated trade-offer labels still use some reduced worker-side text; local trade builder and visible decision tables now show OVR.
• Legacy tutorial/PageHelp/guided-start overlap remains a V3 onboarding pacing review item.