Improve character animations

[Poikilos]

I can do this.

• More exciting walk/run sequences (head & body are perfectly still while limbs move)
• Blend between walk and attack
• Add more attack sequences?

Versions & Hardware

• OpenDungeons-0.7.1-Linux64 & OpenDungeonsPlus-0.7.1 flatpak
• Linux Mint 22.1 Xia based on Ubuntu 24.04 noble based on trixie/sid
• Intel graphics, Intel(R) Core(TM) i5-6400 CPU @ 2.70GHz CPU

[Upabjojr]

The animations live in the exported .skeleton files; improving them means redoing them in the source Blender rigs, which are not in this repository (see #10) — so this is blocked on recovering the asset sources or re-rigging. Not addressable by a code PR.