Polish pounce animation and friendly help

[fortunexbt]

What changed

This is a focused polish pass for the shipped terminal experience.

The play pose now has a small deterministic bounce, a toy that bobs with it, and connected front paws that stay below the face. The old paw coordinates could collide with the head and make the pounce look like disconnected symbols. The README GIF was regenerated from the updated renderer.

The interactive status bar and ambient effects now use the current kitty’s actual seed, so pressing n or letting the screensaver spawn a new kitty no longer leaves stale metadata on screen.

The friendly help output is shorter and keeps compatibility/timing knobs out of the main path without removing support for existing scripts. A CLI regression test protects the compact help and the new play silhouette.

Validation

• make clean && make check
• make sanitize
• regenerated assets/ckitty-demo.gif with make demo
• verified GIF timing remains 0.5 seconds per frame
• visually inspected sit and play demo frames
• git diff --check