Herding / flocking via GeneSociability (boids)

Social species (deer 0.8, wolf 0.6, chicken 0.55, boar 0.3) now school together:
AnimalDecisionSystem scans nearby same-species neighbours (HerdScan) and, when
wandering, a lone social animal steers toward the herd centroid (cohesion) while
close members just mill about (separation). "Safety in numbers" shrinks the
threat-detection radius in a group, so herded prey are calmer and scatter less.
Asocial animals (sociability < 0.3) keep the old random wander. GeneSociability
+ trait; `animal` console prints insulation/sociability. Build + --check-content
clean (42 genes, 41 traits). Not GUI-verified.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Mods/Core/Defs/Animals/Animals.json

@@ -31,7 +31,8 @@
         "GeneGestationDays": 30,
         "GeneLitterSize": 1,
         "GeneHerbivory": 1.0,
-        "GeneToxinTolerance": 0.1
+        "GeneToxinTolerance": 0.1,
+        "GeneSociability": 0.8
       }
     },
 
@@ -64,7 +65,8 @@
         "GeneBreedingSeason": 3,
         "GeneGestationDays": 35,
         "GeneLitterSize": 4,
-        "GeneCarnivory": 1.0
+        "GeneCarnivory": 1.0,
+        "GeneSociability": 0.6
       }
     },
 
@@ -99,7 +101,8 @@
         "GeneHerbivory": 0.4,
         "GeneCarnivory": 0.2,
         "GeneOmnivory": 0.85,
-        "GeneToxinTolerance": 0.25
+        "GeneToxinTolerance": 0.25,
+        "GeneSociability": 0.3
       }
     },
 
@@ -129,7 +132,8 @@
         "GeneLitterSize": 6,
         "GeneHerbivory": 0.8,
         "GeneToxinTolerance": 0.15,
-        "GeneEggLaying": 1.0
+        "GeneEggLaying": 1.0,
+        "GeneSociability": 0.55
       }
     }
   ]