The window.matchMedia API (used for accessibility features) was not
mocked in tests, causing unhandled rejections when replay.ts tried to
check prefers-reduced-motion. Added the mock to both test-setup.ts
and the beforeEach hook in replay.test.ts to ensure it's available
before modules load.
Closes: bf-5cwi
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Updates showLoadError to display a friendly "not available yet" message
for HTTP 404 errors (common for unuploaded replays) vs generic "could
not load" for other HTTP errors. Adds the URL to error output and
maintains HTML escaping.
Also adds vitest testing infrastructure with 5 tests covering:
- 404 not-found message
- Generic HTTP error message
- Parse error handling
- HTML escaping (XSS protection)
- 404 vs error distinction
Closes: bf-5cwi