[A11y] Add Keyboard Navigation Support (Enter/Space) to Notification Preference Toggles

• Labels: good first issue, accessibility, difficulty:beginner, area:core
• Target File: src/components/settings/notification-settings-card.tsx
• Estimated Time: 10–15 minutes
• Difficulty: Level 1 (Beginner)

Why This Matters

Keyboard-only users must be able to toggle notification preferences using standard keyboard controls (Enter and Space).

Current Behavior

Interactive toggle containers in src/components/settings/notification-settings-card.tsx rely primarily on click events.

Requested Change

Add an onKeyDown event handler supporting event.key === 'Enter' || event.key === ' ' for keyboard toggle activation.

Acceptance Criteria

• onKeyDown handler implemented for toggle controls.
• tabIndex={0} present on interactive element containers.
• Verification command passes: npm run test:file -- tests/notifications.test.ts.

Verification

npm run test:file -- tests/notifications.test.ts

Contributor Notes

Accessibility and UX refinement.

🚀 How to Claim and Implement an Issue

1. Choose an Issue: Browse our open issues and pick one matching your interest and available time.
2. Comment on GitHub: Leave a comment on the corresponding GitHub issue: "I would like to work on this issue. Please assign it to me."
3. Follow the Guide: Review our Beginner's Contribution Guide for step-by-step Git instructions.
4. Verify Locally: Run the specific verification command listed on the issue before opening your PR.
5. Submit PR: Open a pull request against main referencing this issue number!

Start in src/components/settings/notification-settings-card.tsx and inspect the interactive notification toggle containers. Add the requested keyboard handling and tabIndex behavior for Enter and Space, then run npm run test:file -- tests/notifications.test.ts. Done means the acceptance criteria pass and the notification toggles support keyboard activation.