fix(pets): keep BitBlob size consistent across actions

[bobleer]

BitBlob visibly changes size when a session moves between idle, working, waiting, review and lifecycle actions. Working frames were oversized, while jump frames had roughly half the idle silhouette area.

Re-register the existing v2 artwork with consistent silhouette area and lower-body anchors, reduce the jump to a 16-pixel hop, and retain all original poses, frame counts and look directions. Play only the sprite animation for the built-in BitBlob so additional CSS mood transforms do not compound its authored motion. Other pets retain their existing presentation.

Validation:

• V2 atlas validation: passed, no errors or warnings; transparent unused cells and edge cleanup verified.
• Independent visual comparison: passed; silhouette-area variation reduced from nearly 3× to about 7% across frames.
• Focused renderer/sprite tests: 10 passed; includes lifecycle actions, gaze and user pets sharing the BitBlob id.
• pnpm run check:web passed; motion inventory reviewed.

Only shared frontend rendering and bundled artwork change. Remote workspace, remote control, peer-device and detached-dispatch paths were not exercised; no transport or persisted format changes.