fix(frontend): disclose notification preference status

[SHAURYAKSHARMA24]

Summary

Makes the planned notification preferences honest and accessible: the section visibly discloses its Coming Soon state, every disabled switch has a unique accessible name and truthful off state, and decorative thumbs are hidden from assistive technology.

Linked issue

Closes #244

Roadmap alignment

• §23 workstream: W4 — trustworthy evidence-led workflows.
• §28 market-fit criterion: Trusted output. The UI no longer implies that unavailable notification preferences are active or configurable.
• Accepted evidence: focused Settings regression coverage, complete frontend gates, and live browser inspection of all three switch contracts and visual positions.

What changed

Frontend

• Added a visible Coming Soon badge and status explanation.
• Added unique accessible names to all three notification switches.
• Declared each switch disabled and aria-checked="false".
• Hid decorative thumbs from assistive technology.
• Corrected each thumb to the left so the visual state matches the programmatic off state.
• Added regression assertions for names, disabled state, ARIA state, decorative content, and off-position styling.

Backend/docs/infra: No changes.

Acceptance criteria completed

• The section visibly discloses that notification preferences are Coming Soon.
• Each switch has a unique accessible name.
• Decorative switch thumbs are hidden from assistive technology.
• Controls remain non-interactive.
• Programmatic and visual states both truthfully communicate off.
• Focused regression coverage is present.
• Frontend unit, lint, and production-build gates pass.
• The final state was inspected in a live browser.

Testing performed

• npm --prefix apps/frontend run test — PASS: 37 files, 210 tests.
• npm run lint:frontend — PASS.
• npm run build:frontend — PASS.
• git diff --check — PASS.
• Live browser verification — PASS: status disclosure visible; three uniquely named switches; all disabled; all expose aria-checked="false"; all thumbs render on the left/off side.

Screenshots

Security and data considerations

• No auth, owner-scoping, secrets, logging, schema, migration, persistence, or backend behavior changed.
• Controls remain disabled and do not simulate saved preferences.

Dependencies and blocked work

None.

Scope changes or remaining work

None for #244.

Contributor checklist

• This PR targets dev
• The issue was assigned/acknowledged before completion
• The branch was created from an up-to-date upstream/dev
• The branch is based on the latest upstream/dev
• This PR addresses one clearly scoped issue
• This PR advances a §23 workstream toward a §28 market-fit criterion
• Every acceptance criterion claimed as complete is complete
• Relevant tests pass
• Documentation is updated for any user-visible behavior that requires documentation
• No secrets, credentials, local env files, or generated build artifacts are included
• No unrelated files were changed
• Closing syntax is used only because the issue is fully resolved
• Dependencies and follow-up work are linked