misc: fix typos in a11y i18n doc comments

[leopoletto]

Summary
Fixes misspellings of “accessibility” (previously written as “accesibility”) across audit source code comments in core/audits/accessibility/*.js.

Why
This is a non-functional change. No audit logic, tests, or runtime behavior are affected. It improves readability and consistency, and also helps localization/i18n workflows that rely on comment strings.

Verification

rg -l -w 'accesibility' core/audits/accessibility/*.js \
  | xargs gsed -i -E 's/\baccesibility\b/accessibility/g'

rg -n -w 'accesibility' core/audits/accessibility/*.js || echo "✅ All fixed"