doxa-maps-spa marks the pane of every tab that has explainer text with data-doxa-help, listens for
doxa:help, and opens the same what/how dialog for the active tab. Closing returns focus to the
exact "?" that opened it (composedPath reaches into the map's shadow root). The top-centre button
and its CSS are gone; a comment for the device-rule toast that sat above the old button's rule
is back on its own rule.
check:help-reachable (gates:pre) keeps it reachable: every map with text has a hosted "?" or a
named help control of its own; the app listens, marks its panes and has no top-centre button; and
the composable, executed on a small fake DOM, dispatches doxa:help bubbling and composed and finds
the host across a shadow root. Six planted defects, each caught.
