Side panel: scrollbar matches the APDU list's width

- the side panel had no scrollbar rule of its own, so it fell back to the
  global 6px default while the APDU list uses 12px; the two now share one
  rule (width 12px, thumb radius 6px = half the bar), so they cannot drift
  apart again — the other panes keep the thin global bar
- Node test pins the shared rule (and the 6px global default)
- SW cache simtrace-analyser-v74 (cosmetic, no version bump)

frontend/index.html

@@ -120,8 +120,10 @@ body { font: 14px/1.5 system-ui, sans-serif; background: var(--bg); color: var(-
 
 /* APDU list */
 .apdu-list { flex: 1 1 0; min-height: 0; overflow-y: auto; padding: 8px; }
-.apdu-list::-webkit-scrollbar { width: 12px; }
-.apdu-list::-webkit-scrollbar-thumb { border-radius: 6px; }
+.apdu-list::-webkit-scrollbar,
+.side-panel::-webkit-scrollbar { width: 12px; }
+.apdu-list::-webkit-scrollbar-thumb,
+.side-panel::-webkit-scrollbar-thumb { border-radius: 6px; }
 .apdu-entry { display: flex; gap: 12px; padding: 3px 12px; border-bottom: 1px solid var(--bg-panel); cursor: pointer; align-items: baseline; }
 .apdu-entry.apdu-pair { background: var(--pair-row); }
 .apdu-entry:hover { background: var(--bg-panel); }