MOSS RGBA - step 14000 continuation

This release adapts the Mage RGBA VAE layers used by CKMoss-Image-RGBA.

Upstream:
- MOSS-Image (c) OpenMOSS Team, https://github.com/OpenMOSS/MOSS-Image, Apache-2.0
- Mage (c) Microsoft, https://github.com/microsoft/Mage, MIT (vendor/MAGE_LICENSE)
- Model code structure follows CKMoss-Image-RGBA (GPLv3), https://github.com/Chenkin-x/CKMoss-Image-RGBA

The released adapter/merged weights are distributed under GPLv3. Upstream
attribution and license terms are retained.