fix(mobile): make usePoseStream read-only

[Gujiassh]

Summary

• remove the duplicate wsService.subscribe() / connect() side effects from usePoseStream
• keep the hook as a pure selector over the pose store, leaving WebSocket lifecycle ownership in App.tsx
• add a focused hook test proving rendering usePoseStream no longer subscribes or reconnects

Validation

• cd ui/mobile && npm test -- --runInBand src/__tests__/hooks/usePoseStream.test.ts
• compatibility lint attempt via ESLINT_USE_FLAT_CONFIG=false npx -y eslint@8 -c .eslintrc.js ... still fails on the repo’s pre-existing ESLint/@typescript-eslint rule mismatch, not on this patch

Notes

• this PR is independent from the open RuView lines #151, #236, and #240; it only touches the passive hook layer under src/hooks/usePoseStream.ts

[Gujiassh]

Follow-up note: I reran the PR-relevant mobile tests locally on this branch: ui/mobile/src/__tests__/hooks/usePoseStream.test.ts and ui/mobile/src/__tests__/screens/MATScreen.test.tsx. Both passed (6 tests total), so the passive-listener/read-only fix is now directly revalidated rather than only inferred from branch history.

[Gujiassh]

Quick sync from my side: this branch is still clean locally and unchanged relative to its fork tracking branch (0/0).

Current state I rechecked today:

• PR is still OPEN + CLEAN
• no local follow-up changes are pending from my side
• there are no active review threads to address

If this looks good on your end, it seems ready for review/merge.

[Gujiassh]

Closing this stale radar lane to keep the authored-PR queue current. I refreshed/revalidated the branch recently, but there has still been no maintainer response on this thread, so I am closing it for now instead of letting it sit indefinitely. If maintainers want this change later, I can reopen or resend it on a fresh branch.