Function
Everything here renders on the server except ModuleRoute. The route and its
progress panel depend on progress stored in the browser, so they are the one
client subtree; the header states only facts the server already knows.
The header carries no decorative hero tile: a Module has no artwork, so a
tile could only repeat the ordinal and a truncation of the title.
Steps were once labelled "Episode N", a term that meant a Module on the
course overview and a Lesson here. See the course-vocabulary capability.
The module overview as a route through its videos: a server-rendered header — back link,
Lesson NN · Courseeyebrow, title, and how many videos the module holds with their total runtime — above the learner's route.