Builds a fenced block. Format: fence + header + "\n" + body + "\n" + fence + "\n" (no space after fence). Picks fence in order: `
if body has no line closing it; else ~~~; else ; else escape body and use `.
| header |
Info string (e.g. "text.oc-frame-primary You said:") |
| body |
Inner content |
|
Full fenced block string |