PR bodies must use Markdown syntax

Always use Markdown syntax in PR bodies: bold, `code`, [text](url), fenced code blocks. Never use org-mode constructs (code, italic, [[id:UUID]] links, #+begin_src).

Why: GitHub renders PR bodies as Markdown, not org-mode. Org constructs appear as raw literal text.

How to apply: Any time writing or editing a gh pr create / gh pr edit body: use Markdown only. The .org recipe file uses org syntax, but the shell strings passed to gh must be Markdown.