- displayHtml uses a dedicated DOMPurify 3.4.16 instance: EDITOR_TAGS, href
only on <a> through isAllowedLink, DROPPED elements go with their content
- string in, string out: parsed into DOMPurify's inert document, nothing
adopted into the live document before binding
- fails closed (empty string) unless isSupported and a fixed canary hold
- Vitest browser mode in Playwright Chromium (npm run test:browser) covers
the clobbering vectors, off-origin form, iframe, meta refresh, links and
the inert parse; happy-dom keeps engine-independent assertions
