Every function the specification declares: each `Module.function/arity` in the first
cell of a table row under spec/*.md, with the numbered section it sits in.
The row grammar is the one spec/README.md §5 asks writers to keep:
|Visualize.Scale.linear/0| contract |. Anything else in a table is not a declaration.
Summary
Functions
Every declaration under root/spec, in file then line order.
Scans one markdown document; file is the path the entries record.