- Replace hide/show visibility approach with dynamic addOutput/removeOutput
and addInput/removeInput for proper pin management
- On node creation, remove all default pins and add only selected ones
- On workflow load (onConfigure), clear all dynamic pins and rebuild from
saved properties
- Remove OUTPUT_NODE from FlakeDataSplitSelect (not an output node)
- Add pin selector UI with +/- buttons that dynamically adds/removes pins
- Export DEFAULT_SPLIT_PINS and DEFAULT_INTO_PINS for use in onConfigure
Closes#139