- add ui/dog_art.py: 12 frames from 236205.gif (64x42, 128-color
palette, transparent background), zlib+base64 embedded
- DogLoader draws half-block truecolor cells over the dimmed dashboard,
transparent background, paw trail 🐾, 40 ms/frame (GIF speed)
- full-screen overlay + input blocking preserved
- tests: frame data + animation; docs updated