feature: add styling foundations

[Pan14ek]

Summary

• add tracked UI-32 through UI-34 refactor tasks
• add task- and lobby-owned CVA badge components
• replace shared conditional class strings with cn()

How to use and test

npm run typecheck
npm run lint
npm run test:run -- src/features/tasks/__tests__/TaskStatusBadge.test.tsx src/features/lobby/__tests__/LobbyTypeBadge.test.tsx
npm run build

Focused regression tests and the production build pass. The full suite retains pre-existing CalendarPage and DashboardPage failures.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud