Scope chartjs-plugin-datalabels to WeatherChart only

Registering the plugin globally on ChartJS attached it to every chart
instance in the app, including the sensor history chart, which then drew
labels on top of every data point. Pass the plugin via the per-instance
'plugins' prop on the WeatherChart's <Chart> instead so unrelated charts
remain unaffected.

Author: eetu

frontend/src/components/WeatherChart.tsx

@@ -24,7 +24,6 @@ ChartJS.register(
   PointElement,
   LineElement,
   LineController,
-  ChartDataLabels,
 );
 
 type WeatherChartData = {
@@ -121,7 +120,8 @@ const WeatherChart: React.FC<WeatherChartProps> = ({
     plugins: {
       legend: { display: false },
       tooltip: { enabled: false },
-      // Disabled by default — re-enabled per-dataset (PV bars only).
+      // Plugin scoped to this chart via the `plugins` prop on <Chart>.
+      // Disabled at chart level — re-enabled per-dataset on PV bars only.
       datalabels: { display: false },
     },
     scales: {
@@ -167,7 +167,14 @@ const WeatherChart: React.FC<WeatherChartProps> = ({
     },
   };
 
-  return <Chart type="bar" options={options} data={chartData}></Chart>;
+  return (
+    <Chart
+      type="bar"
+      options={options}
+      data={chartData}
+      plugins={[ChartDataLabels]}
+    />
+  );
 };
 
 export default WeatherChart;