* fix(markdown): render announcement markdown consistently
- support soft line breaks for announcement markdown without changing the default parser behavior.
- add explicit markdown element styles so lists, tables, code blocks, and quotes render correctly when typography styles are unavailable.
- apply the announcement markdown mode in both the popover and detail dialog for consistent display.
* refactor(markdown): simplify fallback markdown styles
- remove duplicate typography utility classes now covered by explicit markdown element fallbacks.
- keep the markdown renderer behavior unchanged while reducing class noise.
- modernize small helper expressions to satisfy targeted lint checks.
* fix(content): render custom HTML consistently
- add shared rich content rendering so custom HTML and Markdown use the same path across public pages and announcements.
- reuse common URL and HTML detection instead of duplicating content format checks per page.
- keep custom home content inside the standard public layout while preserving full-page iframe rendering for external URLs.
