WebUI: per-signal vscale toolbar, active-signal highlighting, zoom fix

- Per-signal, per-plot vertical scale state (sigVScale keyed by plotId:signalKey)
  so the same signal in two plots has fully independent vscale config
- Active signal redrawn on top of all series with 2× line width for clear
  visual identification; badge click toggles selection and opens/closes the
  embedded vscale toolbar (click same badge again to deselect)
- Vscale configurator moved from floating popup to a slim toolbar strip
  anchored inside the plot card, with an × close button
- Trigger dropdown shows one entry per array signal with [0…N-1] label;
  opening it shows an index-picker dialog to choose the element
- Zoom resampling: when server returns no data for a zoomed range, fall
  back to the local circular buffer instead of returning empty arrays

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Test/MARTeApp/run.sh

@@ -167,7 +167,7 @@ WEBUI_PID=""
 if [ "${START_WEBUI}" -eq 1 ]; then
     echo "==> Starting WebUI on http://localhost:8080..."
     "${WEBUI_BIN}" \
-        --source "Streamer@127.0.0.1:44500" \
+        --source "Streamer@127.0.0.1:44500/239.0.0.1:44503" \
         --source "FastStreamer@127.0.0.1:44501" \
         --source "FullArrStreamer@127.0.0.1:44502" \
         --listen :8080 &