quartoFlavor is set only after a project is compiled with the current
build. Existing Quarto projects that haven't been recompiled have
quartoFlavor=undefined, so the old check (quartoFlavor === 'revealjs')
fell through to the regular PDF compile button with no dropdown.
Drop the quartoFlavor guard — compiler === 'quarto' is sufficient since
all Quarto projects in Verso are RevealJS presentations. Changes applied
to ActionsCell (desktop icon), DownloadPresentationButtonTooltip guard,
and ActionsDropdown (mobile three-dot menu).
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
