016: The pane about the piece: the article's graph, the marks and the cost in the pane

What is asked

The brief's second item (The site is an inbox) and the modes of Ways to read one article: on an article, the pane shows its graph, the reader's marks and decisions, and what it cost; the ways in (headlines, facts, relationships, what is new) computed from the files this site already publishes.

Scenario

Given I am on an article
When I open the pane
Then a Piece tab shows the article's graph drawn from articles/graphs/<slug>.json, my marks on it, and the cost so far
And a row of modes: headlines, facts, relationships, vocabulary, and the five readers' views where they exist