Upgrades WOM from geometry-only (WOM1) to fully animated (WOM2):
- WOM2 magic (0x324D4F57) for animated models, WOM1 for static
- Vertex extended: +boneWeights[4] +boneIndices[4] (40 bytes vs 32)
- Bone data: keyBoneId, parentBone, pivot, flags per bone
- Animation data: per-sequence per-bone keyframes with translation,
rotation (quaternion), scale at millisecond timestamps
- fromM2() now preserves all skeletal data: bone hierarchy, weights,
and per-sequence keyframes from M2 animation tracks
- Backward compatible: WOM1 files load without bone data (32-byte
vertices read and padded with default bone weights)
- FORMAT_SPEC.md updated with WOM2 binary layout