Bug: TO_HEX documentation incorrect — returns lowercase, not uppercase

Summary

The Feldera SQL documentation for binary operations states that TO_HEX returns uppercase hex characters, but the actual behavior returns lowercase.

Documentation claim

From https://docs.feldera.com/sql/binary/:

TO_HEX(x'0abc') => '0ABC'

This implies the output is uppercase.

Actual behavior

CREATE TABLE t (b VARBINARY NOT NULL);
CREATE MATERIALIZED VIEW result AS SELECT TO_HEX(b) AS h FROM t;

INSERT INTO t VALUES (x'48656c6c6f');  -- hex for "Hello"

Expected (per docs): 48656C6C6F
Actual: 48656c6c6f