Parent-Child UI System (#122):
- Add parent weak_ptr to UIDrawable for hierarchy tracking
- Add setParent(), getParent(), removeFromParent() methods
- UICollection now tracks owner and sets parent on append/insert
- Auto-remove from old parent when adding to new collection
Global Position Property (#102):
- Add get_global_position() that walks up parent chain
- Expose as read-only 'global_position' property on all UI types
- Add UIDRAWABLE_PARENT_GETSETTERS macro for consistent bindings
Dirty Flag System (#116):
- Modify markDirty() to propagate up the parent chain
- Add isDirty() and clearDirty() methods for render optimization
Scene as Drawable (#118):
- Add position, visible, opacity properties to Scene
- Add setProperty()/getProperty() for animation support
- Apply scene transformations in PyScene::render()
- Fix lifecycle callbacks to clear errors when methods don't exist
- Add GameEngine::getScene() public accessor
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>
