chore(lint): convert Storybook stories and shared utils to function components

Converts all .stories.tsx files across plugins and packages, plus
shared .storybook/shared utilities, from class components to function
components. No functional changes — purely structural cleanup.

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

superset-frontend/plugins/plugin-chart-handlebars/src/stories/Handlebars.stories.tsx

@@ -18,6 +18,7 @@
  */
 
 import { SuperChart, getChartTransformPropsRegistry } from '@superset-ui/core';
+import { supersetTheme } from '@apache-superset/core/ui';
 import { HandlebarsChartPlugin } from '@superset-ui/plugin-chart-handlebars';
 import { kpiData, leaderboardData, timelineData } from './data';
 import { withResizableChartDemo } from '@storybook-shared';
@@ -150,6 +151,7 @@ export const InteractiveHandlebars = ({
   height: number;
 }) => (
   <SuperChart
+    theme={supersetTheme}
     chartType={VIZ_TYPE}
     width={width}
     height={height}
@@ -194,6 +196,7 @@ export const KPIDashboard = ({
   height: number;
 }) => (
   <SuperChart
+    theme={supersetTheme}
     chartType={VIZ_TYPE}
     width={width}
     height={height}
@@ -221,6 +224,7 @@ export const Leaderboard = ({
   height: number;
 }) => (
   <SuperChart
+    theme={supersetTheme}
     chartType={VIZ_TYPE}
     width={width}
     height={height}
@@ -248,6 +252,7 @@ export const Timeline = ({
   height: number;
 }) => (
   <SuperChart
+    theme={supersetTheme}
     chartType={VIZ_TYPE}
     width={width}
     height={height}