Refactor(files-util): Optimize the regular expression to match "import react"

src/components/Playground/files.ts

@@ -106,7 +106,7 @@ export const cssToJs = (file: IFile) => {
 }
 
 export const addReactImport = (code: string) => {
-    if (!/import\s+React/g.test(code)) {
+    if (!/^\s*import\s+React\s+/g.test(code)) {
         return `import React from 'react';\n${code}`
     }
     return code