* fix(web): replace mermaid bomb-icon error flood with toast notifications
mermaid.render() called without a container leaves orphaned error
elements (with bomb icons) in document.body on parse failures. Clean up
these orphans after every render and show an error toast instead.
* fix(web): address PR review — prevent toast flooding, include error detail, add hook tests
- Add latestRenderId guard in TipTap MermaidNodeView to skip stale
renders, preventing toast spam on every keystroke
- Include mermaid error message in toast description via CustomEvent detail
- Add useMermaidErrorToast hook tests (event listener + cleanup)
* style(web): format mermaid-error-toast test with prettier
* fix(web): include error message in MermaidBlock toast description