fix(mobile): clean up sockets when simulation starts

[Gujiassh]

Summary

• close the active WebSocket and clear pending reconnect timers when the settings URL is emptied and the client switches back to simulation mode
• add a focused websocket-service regression covering both active-socket cleanup and pending reconnect cancellation
• keep the patch isolated to ws.service.ts, separate from open RuView PR scopes #151 and #236

Validation

• cd ui/mobile && npm test -- --runInBand src/__tests__/services/ws.service.test.ts
• ESLINT_USE_FLAT_CONFIG=false npx -y eslint@8 -c .eslintrc.js src/services/ws.service.ts src/__tests__/services/ws.service.test.ts (still fails because of a pre-existing repo ESLint/@typescript-eslint rule wiring mismatch, not because of this patch)

Notes

• this fix specifically covers the “switch from reconnecting/connected socket to empty URL” case that the existing simulation-mode tests did not exercise

[Gujiassh]

Quick validation from my side on the current branch tip:

• cd ui/mobile && node ./node_modules/jest/bin/jest.js --runTestsByPath src/__tests__/services/ws.service.test.ts → 8 passed

So the websocket cleanup behavior covered by this PR is locally green on the current head.

[Gujiassh]

Closing this stale radar PR to keep the queue clean: it has been open for weeks without maintainer response, and I am not going to keep it in the active follow-up set without renewed upstream interest.