Cross-run variance map

Availability

Component files exist (ui/views/variance_map.py, frontend/src/components/charts/VarianceMap.tsx) but neither is currently wired into the active SPA layout or the run.py Marimo notebook. The closest shipping visual in the SPA is the consensus view.

Per-offset byte variance across N runs plotted as a log-y bar chart. Variance thresholds 200 and 3000 separate STRUCTURAL, POINTER, and KEY_CANDIDATE classes.

To render it today, import the component directly into a custom Marimo cell or add it to frontend/src/components/layout/Workspace.tsx.