JJ: Farm and agriculture

Bug Fix Update

* Pregnant sheep now sleep normally at night again. They will only stay awake during labor or during the final stage of pregnancy, matching the behavior of pigs and horses.
* Pick Block now returns the correct JJ Farms spawn egg.
* Pick Block now also preserves the selected animal's variant instead of always giving the default one.
* Spawn eggs now create babies when used on an adult of the same species, matching vanilla behavior.
* Added support for Superflat worlds: in newly generated Superflat chunks, the mod will attempt to spawn small groups of the main JJ Farms animals on grass in a lightweight and controlled way.
* The maximum sheep herd size has been reduced to **6 individuals** to prevent overcrowding.
* Once a herd reaches 6 sheep, any additional nearby sheep will form a new herd, creating more natural, fluid, and stable herd behavior in Survival mode.
* Fixed several issues related to sheep.
* Improved the AI of various mobs.
* Fixed bugs affecting the behavior of multiple entities.
* General performance optimizations.
* Stability improvements and general bug fixes.