web: export menu, slice 11 of M3

The toolbar's Export button becomes a real menu: Data (JSON) downloads
{ base, panels, results } exactly as held in the store, Per-node CSV
writes one row per panel and node (educated flag, reachedAtRound with
-1 kept), and Picture (PNG) rasterizes each panel's live SVG with the
current theme's token values resolved, drawn side by side with labels
and the live percentage at the current round, plus legend and the
disclaimer footer line, at 2x. Items disable while a run is in flight
so exports always capture settled state.

web/src/components/ScenarioPanel.vue

@@ -67,7 +67,11 @@ const numStudents = computed(() => store.effectiveConfig(props.panel).numStudent
 const reachedCount = computed(() => {
   const panelResult = result.value
   return panelResult
-    ? reachedCountDisplayed(panelResult.reachedAtRound, store.state.round, store.state.roundProgress)
+    ? reachedCountDisplayed(
+        panelResult.reachedAtRound,
+        store.state.round,
+        store.state.roundProgress,
+      )
     : 0
 })
 const reachedPctNow = computed(() => (reachedCount.value / numStudents.value) * 100)