Add custom plotting support for vehicle signal

- Plot pie chart for engine load state

main.py

@@ -410,12 +410,10 @@ def update_corr(method, target, vehicle, bus, tab):
     Input('vehicles-vehicle-selector', 'value')
 )
 def render_vehicles(vehicle):
-    """Render small graph boxes for every decoded signal, combining both buses."""
     if not vehicle or vehicle not in DATA:
         return html.Div("No data available", className="text-muted")
 
     brand = VEHICLE_META.get(vehicle, {}).get("brand", "")
-
     vehicle_module = get_vehicle_module(brand)
 
     dfs = []
@@ -431,13 +429,22 @@ def render_vehicles(vehicle):
         df = df.sort_values('Timestamp', kind='stable').reset_index(drop=True)
 
     cards = []
+
     for nid, frame_def in vehicle_module.DECODER_RULES.items():
         decoded = vehicle_module.decode_dataframe(df, frame_def.can_id)
 
-        for sig in frame_def.signals:
-            unit_str = f" ({sig.unit})" if sig.unit else ""
-            title = f"{frame_def.can_id} - {sig.name}{unit_str}"
-            fig = vehicle_module.plot_signal(decoded, sig.name, title=title, color=frame_def.color)
+        for item in frame_def.signals:
+            if hasattr(item, 'plot_func') and callable(item.plot_func):
+                title = f"{frame_def.can_id} - {item.name}"
+                fig = item.plot_func(decoded, frame_def.color)
+            else:
+                sig = item
+                if getattr(sig, 'skip_plot', False):
+                    continue
+
+                unit_str = f" ({sig.unit})" if sig.unit else ""
+                title = f"{frame_def.can_id} - {sig.name}{unit_str}"
+                fig = vehicle_module.plot_signal(decoded, sig.name, title=title, color=frame_def.color)
 
             card = dbc.Card([
                 dbc.CardBody([