fix: use computed color scheme in system resources charts

useMantineColorScheme() returns 'auto' when system mode is active,
causing the chart background color to fall through to the light variant.
Switch to useComputedColorScheme() which always resolves to the actual
'light' or 'dark' value, keeping charts visually correct in all modes.

packages/widgets/src/system-resources/chart/common-chart.tsx

@@ -2,7 +2,7 @@
 import type { ReactNode } from "react";
 import type { AreaChartSeries } from "@mantine/charts";
 import { AreaChart, LineChart } from "@mantine/charts";
-import { Card, Center, Group, Loader, Stack, Text, useMantineColorScheme, useMantineTheme } from "@mantine/core";
+import { Card, Center, Group, Loader, Stack, Text, useComputedColorScheme, useMantineTheme } from "@mantine/core";
 import { useElementSize, useHover, useMergedRef } from "@mantine/hooks";
 import type { TooltipProps, YAxisProps } from "recharts";
 
@@ -36,14 +36,13 @@ export const CommonChart = ({
 }) => {
   const { ref: elementSizeRef, height } = useElementSize();
   const theme = useMantineTheme();
-  const scheme = useMantineColorScheme();
+  const colorScheme = useComputedColorScheme("light");
   const board = useRequiredBoard();
   const { hovered, ref: hoverRef } = useHover();
   const ref = useMergedRef(elementSizeRef, hoverRef);
 
   const opacity = board.opacity / 100;
-  const backgroundColor =
-    scheme.colorScheme === "dark" ? `rgba(57, 57, 57, ${opacity})` : `rgba(246, 247, 248, ${opacity})`;
+  const backgroundColor = colorScheme === "dark" ? `rgba(57, 57, 57, ${opacity})` : `rgba(246, 247, 248, ${opacity})`;
 
   const ChartComponent = chartType === "line" ? LineChart : AreaChart;
   const showIcon = labelDisplayMode === "icon" || labelDisplayMode === "textWithIcon";