[#249] Fix terminal WebSocket ready state check

[realproject7]

Summary

• replace server-side WebSocket.OPEN usage with a runtime-safe numeric readyState helper
• add a regression test covering open/connecting/closing/closed socket states
• keep browser-side terminal code unchanged, where WebSocket.OPEN is valid

Verification

• npm test -- --run app/routes/terminal.test.ts
• npm run typecheck
• npm run lint
• npm run app:dev, then curl http://localhost:7777/api/auth/status and http://localhost:5173/api/auth/status

Closes #249