Fixed markdown preview for comments by replacing marked.parse() calls
with parseMarkdown() function. The application uses a custom markdown
parser (markdown.js), not the marked.js library.
Changes:
- togglePreview(): Use parseMarkdown() instead of marked.parse()
- updatePreview(): Use parseMarkdown() instead of marked.parse()
Resolves issue where markdown preview didn't work for comments but
worked after posting.
Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>