Add experimental V12 native context and guider source
Add six versioned developer nodes for same-context source/donor/pole studies,
owned hook cleanup, native output projection, pinned native Euler guider
consumption and owned optional donor removal.
Preserve V9/V10/V11/Slider V1 and existing recipe defaults. V12 remains
experimental; this source delivery does not establish installed-runtime,
model-task or visual calibration support.
Validation: 145 host-free contract tests, required compile check and local
Comfy CLI metadata validation.
Kevin Gilper
f7f3b163f7