[refactor] Drop XQuery 4.0 binary type promotion blocks

Per @duncdrum and @line-o on PR eXist-db#6344: both reviewers flagged the two
xs:hexBinary ↔ xs:base64Binary code paths as XQ 4.0-specific (the
comments literally say "(XQuery 4.0)") and noted they don't belong in
this XQ 3.1 conformance subset. Removed:

- DynamicTypeCheck.java: the xs:base64Binary ↔ xs:hexBinary type-promotion
  branch in the static-type-check ladder
- GeneralComparison.java: case (d) of resolveNumericType — cast both
  operands of a general comparison to xs:base64Binary when both are
  binary types. Renumbered the now-final XPTY0004 case from (e) to (d).

These will be reintroduced together with the rest of XQ 4.0 type
coercion in v2/xq4-core-functions (PR eXist-db#6260).

XQuery3Tests: 1030/1030 pass.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: joewiz

exist-core/src/main/java/org/exist/xquery/DynamicTypeCheck.java

@@ -149,15 +149,6 @@ private void check(Sequence result, Item item) throws XPathException {
             } else if (type == Type.ANY_URI && requiredType == Type.STRING) {
                     item = item.convertTo(Type.STRING);
                     type = Type.STRING;
-            //Binary type promotion (XQuery 4.0): xs:base64Binary ↔ xs:hexBinary
-            } else if ((type == Type.BASE64_BINARY && requiredType == Type.HEX_BINARY)
-                    || (type == Type.HEX_BINARY && requiredType == Type.BASE64_BINARY)) {
-                try {
-                    item = item.convertTo(requiredType);
-                } catch (final XPathException e) {
-                    throw new XPathException(expression, ErrorCodes.XPTY0004,
-                            "cannot convert " + Type.getTypeName(type) + " to " + Type.getTypeName(requiredType));
-                }
             } else {
                 if (!(Type.subTypeOf(type, requiredType))) {
                     throw new XPathException(expression, typeMismatchError,

exist-core/src/main/java/org/exist/xquery/GeneralComparison.java

@@ -1082,17 +1082,7 @@ private AtomicValue convertForValueComparison(final AtomicValue value, final int
             }
 
             /*
-             *  d. (XQuery 4.0) If each operand is an instance of one of the types
-             *     xs:hexBinary or xs:base64Binary, then both operands are cast to
-             *     type xs:base64Binary.
-             */
-            if ((thisType == Type.HEX_BINARY || thisType == Type.BASE64_BINARY)
-                    && (otherType == Type.HEX_BINARY || otherType == Type.BASE64_BINARY)) {
-                return value.convertTo(Type.BASE64_BINARY);
-            }
-
-            /*
-             *  e. Otherwise, a type error is raised [err:XPTY0004].
+             *  d. Otherwise, a type error is raised [err:XPTY0004].
              */
             throw new XPathException(this, ErrorCodes.XPTY0004, "Incompatible primitive types");
         }