0.2.0

• Map annotated string enumerations onto synthesized StringSchema metadata while preserving their CompositeSchema tree.
• Add CompositeSchema::stringEnum() for closed and open annotated enums.
• Derive enum type names from composite titles and value names from branch titles.
• Keep vendor extensions opaque instead of interpreting enum metadata from x-enum-name and x-enum-keys.
• Reject malformed annotated enum unions with source JSON Pointer context.

This is a breaking release. Consumers using enum vendor extensions should migrate their specifications to annotated enumerations before upgrading.