apps/chat: hide SSR talent markdown until bootstrap renders it
Server-rendered talent summary and reason cells briefly showed raw markdown characters before the bootstrap pass ran renderMarkdown over them. Hide markdown-marked nodes until bootstrap removes the marker, eliminating the flash. Live-appended cards already render through renderMarkdown directly and are unaffected.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>