R-package docs.yaml installs the nonexistent R package quarto-dev/quarto, so the altdoc docs job fails #1137

The docs job (altdoc site build) fails in "Install R dependencies" in four R-package repos whose .github/workflows/docs.yaml lists quarto-dev/quarto under extra-packages:

• pr.helpers
• rmb
• gdl
• snapr

Log of pr.helpers job 118028885891:

Could not solve package dependencies:
* quarto: Conflicts with quarto-dev/quarto
* quarto-dev/quarto: ! pkgdepends resolution error for quarto-dev/quarto.
! Can't find R package in GitHub repo quarto-dev/quarto

quarto-dev/quarto has no R package; the R package is quarto-dev/quarto-r, which rpt, gw and qnp already use. The failure shows on PRs (for example pr.helpers#6, rmb#23, gdl#6) and blocks any PR in those repos from a green docs check.

Fix: replace quarto-dev/quarto with quarto-dev/quarto-r in the four workflows, one PR per repo. A longer-term fix is to move the altdoc docs workflow into a reusable workflow so the list is not copied per repo; gha#1136 does that for R-check-docs.