Dashboard: Use monotone curve type for AreaChart to avoid clipping (#8329)

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## PR-Codex overview

This PR focuses on updating the `type` property for charts from `natural` to `monotone` in various components to improve the visual representation of the data.

### Detailed summary

- In `empty-chart-state.tsx`, changed `type` from `natural` to `monotone`.
- In `area-chart.tsx`, changed `type` from `natural` to `monotone`.
- In `ErrorRate.tsx`, changed `type` from `natural` to `monotone`.

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<!-- This is an auto-generated comment: release notes by coderabbit.ai -->

## Summary by CodeRabbit

* **Style**
  * Updated chart line rendering across multiple dashboard components for improved visual consistency. Area and bar charts now use refined curve interpolation for smoother data visualization.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Author: MananTank

apps/dashboard/src/@/components/analytics/empty-chart-state.tsx

@@ -95,7 +95,7 @@ function SkeletonBarChart(props: {
             fill={`url(#${fillAreaSkeletonId})`}
             radius={8}
             stroke="hsl(var(--muted-foreground))"
-            type="natural"
+            type="monotone"
           />
         </AreaChart>
       )}

apps/dashboard/src/@/components/blocks/charts/area-chart.tsx

@@ -172,7 +172,7 @@ export function ThirdwebAreaChart<TConfig extends ChartConfig>(
                     key={key}
                     stackId={props.variant !== "stacked" ? undefined : "a"}
                     stroke={`var(--color-${key})`}
-                    type="natural"
+                    type="monotone"
                   />
                 ),
               )}

apps/dashboard/src/app/(app)/team/[team_slug]/[project_slug]/(sidebar)/engine/(instance)/[engineId]/metrics/components/ErrorRate.tsx

@@ -59,7 +59,6 @@ export function ErrorRate({ datapoints }: { datapoints: ResultItem[] }) {
           key={tag}
           stackId="a"
           stroke={`var(--color-${tag})`}
-          type="natural"
         />,
       );
     }