refactor: refactor to clean up and simplify things

src/merkle/mod.rs

@@ -102,3 +102,7 @@ const fn int_to_node(value: u64) -> RpoDigest {
 const fn int_to_leaf(value: u64) -> Word {
     [Felt::new(value), ZERO, ZERO, ZERO]
 }
+
+pub fn digests_to_words(digests: &[RpoDigest]) -> Vec<Word> {
+    digests.iter().map(|d| d.into()).collect()
+}