✨(frontend) create a new primitive Switch

Inspired by Robin's design, I've styled a React Aria
Switch component using our DSFR theme.

This is an initial draft and isn't yet pixel-perfect compared
to Robin's design. It also hasn't been integrated into
the form inputs yet.

src/frontend/src/primitives/Switch.tsx

@@ -0,0 +1,69 @@
+import {
+  Switch as RACSwitch,
+  SwitchProps as RACSwitchProps,
+} from 'react-aria-components'
+import { styled } from '@/styled-system/jsx'
+import { StyledVariantProps } from '@/styled-system/types'
+import { ReactNode } from 'react'
+
+export const StyledSwitch = styled(RACSwitch, {
+  base: {
+    display: 'flex',
+    alignItems: 'center',
+    gap: '0.571rem',
+    color: 'black',
+    forcedColorAdjust: 'none',
+    '& .indicator': {
+      width: '2.6rem',
+      height: '1.563rem',
+      border: '0.125rem solid',
+      borderColor: 'primary.800',
+      borderRadius: '1.143rem',
+      transition: 'all 200ms, outline 200ms',
+      _before: {
+        content: '""',
+        display: 'block',
+        margin: '0.125rem',
+        width: '1.063rem',
+        height: '1.063rem',
+        borderRadius: '1.063rem',
+        background: 'primary.800',
+        transition: 'all 200ms',
+      },
+    },
+    '&[data-selected] .indicator': {
+      borderColor: 'primary.800',
+      background: 'primary.800',
+      _before: {
+        background: 'white',
+        transform: 'translateX(100%)',
+      },
+    },
+    '&[data-disabled] .indicator': {
+      borderColor: 'primary.200',
+      background: 'transparent',
+      _before: {
+        background: 'primary.200',
+      },
+    },
+    '&[data-focus-visible] .indicator': {
+      outline: '2px solid!',
+      outlineColor: 'focusRing!',
+      outlineOffset: '2px!',
+    },
+  },
+  variants: {},
+})
+
+export type SwitchProps = StyledVariantProps<typeof StyledSwitch> &
+  RACSwitchProps & { children: ReactNode }
+
+/**
+ * Styled RAC Switch.
+ */
+export const Switch = ({ children, ...props }: SwitchProps) => (
+  <StyledSwitch {...props}>
+    <div className="indicator" />
+    {children}
+  </StyledSwitch>
+)

src/frontend/src/primitives/index.ts

@@ -29,3 +29,4 @@ export { ToggleButton } from './ToggleButton'
 export { Ul } from './Ul'
 export { VerticallyOffCenter } from './VerticallyOffCenter'
 export { TextArea } from './TextArea'
+export { Switch } from './Switch'