feat: add parseOptional method (try-parse pattern)

[neewrobert]

Summary

Currently, RangeParser.parse() throws RangeParseException on invalid input. A common use case is to attempt parsing without exception handling.

Proposal

Add a method that returns Optional<Range<T>> instead of throwing:

Optional<Range<Integer>> range = parser.parseOptional("[1..10]", Integer.class);

This follows the try-parse pattern common in Java libraries and is useful for:

• Validating user input without try/catch
• Stream processing where invalid ranges should be filtered
• Optional configuration values