Feature: Markdown Help

Formatting reference for posts, messages, and descriptions.

Where: /help/markdown

Supported syntax:

• **bold**, *italic*, ~~strikethrough~~
• `inline code`
• Fenced code blocks with language hints: ```c … ```
• [link text](https://url)
• @username → profile mention (sends a notification)
• ![alt](image-url) for images
• > quote for blockquotes
• - item or 1. item for lists
• | a | b | with | --- | --- | for tables
• --- for horizontal rules
• :smile: and other emoji shortcodes
• [video](youtube-url) → embedded video player

Syntax highlighting: fenced code blocks with a language hint are rendered with Prism-based syntax coloring.

Link previews: paste a URL on its own line; the server fetches and renders a card with the title, description, and thumbnail.