Richer task descriptions and comments with Markdown

Task descriptions and comments now render Markdown — headings, lists, links, bold, inline code — so a task can carry real structure instead of one long paragraph.

How it works

• Write plain text as before; the formatting renders when you save.
• Long descriptions get an expandable editor, and the rendered text sits in its own panel on the task drawer.
• Formatting is limited to safe Markdown — raw HTML is ignored.