fix loading bug: use script tags for embedded markdown

The previous approach embedded markdown as JS string literals, but
unescaped quotes in the content caused syntax errors that prevented
the page from rendering. Now uses <script type="text/x-markdown">
tags which avoid all escaping issues — the browser treats the content
as plain text and JS reads it via .textContent.

https://claude.ai/code/session_01BgQZR5yFQxP94gNvDkvavs

Author: claude