Feat: Modify the background color of the agent canvas #3221 (#9020)

### What problem does this PR solve?

Feat: Modify the background color of the agent canvas #3221
### Type of change


- [x] New Feature (non-breaking change which adds functionality)

web/src/components/cross-language-form-field.tsx

@@ -57,6 +57,7 @@ export const CrossLanguageFormField = ({
               maxCount={100}
               {...field}
               onValueChange={field.onChange}
+              defaultValue={field.value}
               modalPopover
             />
           </FormControl>