ArenaMW native animation integration - Sit Down Please 3.5.1

Source package supplied by the user: Sit Down Please 3.5.1.

Integrated scope:
- KF/YAML animation sources for the normal, female, beast and Khajiit actor skeleton folders.
- Selected safe sitting/resting/social animations in the Z player animation menu.
- Safe standing sermon/social gestures in NPC ambient behaviour when another living NPC is nearby.

Not integrated:
- The original OpenMW-Lua scripts.
- Furniture profile/placement logic, automatic chair ownership, bed routing or lecture sessions.
- Seated audience animations are not randomly started for standing NPCs; doing so without furniture alignment would place them in mid-air.

The original assets remain the work of their respective author(s). Before publishing a build that redistributes these assets, verify the original mod's redistribution permissions.
