Addresses follow-up issues from PR #44 bot review:
- Add parentId field to AXNode (walk DOM ancestors to resolve AX parent)
- Omit optional fields when empty (name, value, properties, childIds)
instead of emitting null/empty arrays, per CDP spec
- Add ax_value_boolean() and ax_value_integer() helpers for consistent
AXValue construction across all property types
- Use typed helpers throughout compute_properties() instead of inline
JSON construction
CDP spec reference: Accessibility.AXNode requires parentId as AXNodeId,
and optional fields should be absent when not applicable.
Co-authored-by: zhangyang-crazy-one <[email protected]>
