A route tile restored (or opened) before its plugin route registered kept the
humanized-path fallback as its tab title forever: paneMirror recomputes titles
only when one of its atoms changes, and watchRouteTiles listened to $routeTiles
alone. #112147 made the pane CONTENT heal on late registration; the title
still lagged.
routes.ts exposes $routesVersion, an atom bumped from registry.subscribeArea
(ROUTES_AREA) only while listened to, and watchRouteTiles passes it as `also`
so the sync re-runs and the pane re-registers with the contribution's title.
One test, red on origin/main.
c91770b268