Retire dormant prompt compatibility APIs

internal/generatedtext/json.go

@@ -89,11 +89,3 @@ func requireGeneratedTextStringField(data []byte, name, field string) error {
 	}
 	return nil
 }
-
-func normalizeGeneratedText[T any](value T, name string) ([]byte, error) {
-	normalized, err := json.Marshal(value)
-	if err != nil {
-		return nil, fmt.Errorf("normalize %s generated text: %w", name, err)
-	}
-	return normalized, nil
-}