[CHORE] Add axe-core / WCAG AA automated accessibility tests to CI

[lowlydba]

Background

Color contrast and other accessibility violations are not currently caught by CI. A WCAG AA contrast failure on the community page filter pills was only surfaced by a Copilot code review, not by any automated check.

Goal

Wire @axe-core/react into the existing vitest/jsdom test suite so that WCAG AA violations (contrast, missing labels, invalid ARIA, etc.) fail CI automatically.

Suggested approach

1. Install @axe-core/react (or jest-axe, which also works with vitest)
2. Add a smoke-test that renders key interactive components (CommunityTable, homepage, etc.) and asserts toHaveNoViolations() with ruleset wcag2aa
3. Enforce in the existing Test workflow — no new workflow needed

Acceptance criteria

• At least CommunityTable and any other components with custom styling are covered
• Violations at WCAG AA level fail the Unit tests CI check
• README or a comment in the test file documents how to run locally and how to suppress known false positives if needed

References

• https://github.com/dequelabs/axe-core
• https://github.com/nickvdyck/vitest-axe (vitest-native alternative)
• Triggered by contrast issue found in PR [FEATURE] Convert Community page to filterable card grid #403