#1831 Data Tutorial copy cmd only copies half of data query

Bug: On https://swamp-club.com/manual/tutorials/working-with-data, the copyable command $ swamp data query 'tags.type == "resource"' copies only swamp data query 'tags.type == \ when you click the block / COPY affordance.

Cause: .copy-cmd copies data-cmd via getAttribute. The attribute is emitted as data-cmd="... "resource" ...". HTML does not treat " as an escape, so the attribute is truncated at the first inner ", and resource"' becomes a stray boolean attribute. Visible text in the

 is complete; only copy is wrong.

Repro: Open that tutorial, hover the query command until COPY appears, click, paste. Other commands on the page copy in full.
Fix: Emit " (or copy pre.textContent with the $  stripped). Add a test for nested double quotes.