[Blazehue]

What does this PR do?

If a participant's socket had dropped, tapping an answer used to mark it as chosen even though nothing was sent. ws?.send on a closed socket does nothing and doesn't throw, so the answer was lost without any sign. The host's Start and Next controls had the same problem.

• Start, next question and submit answer in LiveQuiz.tsx now all go through one sendMessage() helper. It checks ws.readyState === WebSocket.OPEN and returns whether the message was sent.
• When a send is refused, an inline role="alert" message appears beside the control. The answer stays selectable, so the participant can try again.
• The answer buttons, Start Game, Show Standings → and Next Question are disabled while connectionState is not 'connected', and the reason is shown next to them.
• handleNext only advances qIndex after the send succeeds, so a failed Next no longer skips a question.
• The issue asked for a decision on this: an answer tapped while disconnected is refused, not queued. A queued answer could arrive after the question has closed, and its timeMs would no longer mean anything.
• Not changed: the automatic first quiz:next-question sent 3s after quiz:start, because no user tap is involved.

No screenshots: the only visual change is one line of red helper text under the disabled controls, using the existing text-red-400 style.

Related issue

Closes #175

Type of change

• Bug fix
• New feature
• Documentation
• Refactoring
• Performance
• Tests
• Build / CI / deployment

Which services does this touch?

• apps/frontend
• apps/http-server
• apps/ws-server
• apps/genAI
• packages/db (schema or Prisma changes)
• Docker / CI

How did you test this?

New component tests in LiveQuiz.test.tsx use the FakeSocket stub. They cover:

• an answer sent while connected
• an answer refused when the socket is closed before onclose fires
• answers disabled after the connection drops
• Start Game disabled after the connection drops
• Next not skipping a question when the send fails

Commands run:

• cd apps/frontend && npx vitest run: pass (9 files, 89 tests)
• The new LiveQuiz tests were also run against the unfixed LiveQuiz.tsx from main. As expected, 4 of them fail there, and they pass with the fix.
• pnpm run check-types --force: pass (9/9 tasks)
• pnpm run build --filter='!admin' --filter='!admin-server' --force: pass (5/5 tasks)
• npx eslint src/screens/LiveQuiz.tsx src/screens/LiveQuiz.test.tsx: 6 errors and 1 warning, the same as on main and all on untouched lines. Nothing new (CI lint is report-only).

Not checked in a browser, and not tested with more than one participant. The behaviour is covered only by the component tests.

Checklist

• I ran pnpm run lint (only ran eslint on the two changed files; see above)
• I ran pnpm run check-types
• I ran pnpm run build (ran it without admin and admin-server; see above)
• The app still starts with docker-compose up
• I updated documentation if this changes behaviour or setup
• I did not commit any .env file, API key or other secret