Several dangerouslySetInnerHTML sinks rendered user-controlled strings (chat messages, usernames, chat history) without sanitisation, relying implicitly on upstream formatting or server-side charset limits. Route them all through the existing SanitizeHtml (DOMPurify) helper so the security guarantee is local to each render site.
Sinks fixed: ChatWidgetWindowView (name/message/original/translated), ChatHistoryView (name/message), AvatarInfoWidgetNameView + AvatarInfoWidgetAvatarView (username), SelectReportedUserView (username).
Add regression suites: SanitizeHtml.test.ts (XSS neutralised, chat markup preserved) and RoomChatFormatter.test.ts (pins the existing encodeHTML defence). No behaviour change: SanitizeHtml's allow-list keeps the b/i/u/span/strong/em/br markup the chat/profile UI relies on.