fix: restore React value import in CallToActionSection

Biome auto-fix split 'import React, { useState }' into a type-only
'import type React' plus a value 'import { useState }'. Jest uses the
classic JSX transform which requires React as a runtime value in scope;
the type-only import stripped it out, causing ReferenceError in tests.

Author: blarghmatey

frontends/main/src/page-components/LearningResourceExpanded/CallToActionSection.tsx

@@ -1,6 +1,5 @@
 import { env } from "@/env"
-import type React from "react"
-import { useState } from "react"
+import React, { useState } from "react"
 import styled from "@emotion/styled"
 import { default as NextImage } from "next/image"
 import { useFeatureFlagEnabled, usePostHog } from "posthog-js/react"