The viewer threads the model's doc through normalizeModel into both
composite view states — appended to INFO.B (collapsed box) and INFO.C
(expanded cluster frame) — and shows the root composite's doc as a muted
header line (#rootdoc span in GRAPH_HEAD, empty when absent; the DOM
population sits in the browser-only block, the same boundary as the
breadcrumb). viewer_tooltip.mjs pins the doc'd cases beside the
byte-exact un-doc'd pins; sample-model.json gains the additive doc key;
e2e drives aura graph over a nested-doc blueprint into the emitted page.
closes#125
The headless viewer suite covered only the DOT half (normalizeModel/
genDot); the tooltip half — INFO.B (collapsed), INFO.C (expanded
cluster), INFO.P (ports), and md()'s markdown-to-HTML step — was
asserted by no test. viewer_tooltip.mjs pins the current shapes;
graph-viewer.js only hoists md() above the browser guard and exports
it (location-only move, no behaviour change), so the pin can drive the
real conversion headlessly. Surfaced by the grounding-check on the #125
composite-doc spec: its viewer assumptions had no current-behaviour pin.
refs #125
Brummel