Replace the ascii-dag aura graph view with a homogeneous pin-graph: aura emits a
deterministic JSON model (hand-rolled, RunReport::to_json house style, no serde);
a vendored viewer JS (genDot, ported from the prototype) turns it into DOT;
Graphviz-WASM lays out + draws it in the browser. aura stays a read-only
serializer (C9), ships no layout engine. The golden-tested contract is the JSON
model. Iteration 1: the model serializer + golden/determinism/read-only tests.
Iteration 2: viewer + WASM vendoring + self-contained HTML, retire ascii-dag.
Grounding-check PASS; design ratified interactively against the 0026 prototype.