fix(a11y): omit aria-controls on inactive tabs to prevent broken tabpanel references - #721

Summary

Fixes #710.

In tabs consumers such as ContributorDashboardClient, only the currently active tabpanel is mounted in the DOM. Previously, every tab rendered an aria-controls attribute pointing to its tabpanel id regardless of whether that panel existed in the DOM, triggering axe ARIA reference violations and misleading assistive technology.

Changes

• In src/components/ui/Tabs.tsx, omit aria-controls on inactive tabs so only the active tab points to its mounted panel.
• Added tests in src/components/ui/Tabs.test.tsx ensuring aria-controls is rendered only on the active tab and updates on tab switch.

Verification

• Ran Jest: 17/17 tests pass in src/components/ui/Tabs.test.tsx.
• Ran Jest: 5/5 tests pass in src/app/dashboard/contributor/ContributorDashboardClient.test.tsx.
• Ran ESLint: 0 errors.