Ignore the vitest coverage report

pnpm test:coverage writes here and it was never excluded, so it was one
git add -A away from getting committed.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

Author: shixish

.gitignore

@@ -1,5 +1,6 @@
 node_modules/
 dist/
+coverage/
 *.tsbuildinfo
 .DS_Store
 fixtures/*/.wrangler*