Delete HardpointTransforms; mount direction and arc become sim data

Entity.HardpointTransforms was written only by Unity (EntityInstance.cs),
so the simulation's notion of where a gun points was a readback from a
renderer that never runs headless -- Combat.cs threw KeyNotFoundException
on the first combat tick outside Unity. Deletes the field, its writer, and
the readback branch in Behavior.Direction, leaving the item-rotation path
(the same convention reaction thrusters use, R6) as the only source of
mount direction.

Adds FireControl (ServerShared), a static class owning whether a weapon
bears on a point: MountDirection (planar, from ItemRotation), ArcFor (the
per-hardpoint HardpointData.FiringArc override, falling back to the new
GameplaySettings.FiringArc default of 120), and InArc (the planar dot-cone
test, R7 -- target height never enters it, and an arc of 360+ passes
unconditionally so a turret hardpoint needs no new type, just a number).
Combat.cs and TurretController.cs now gate AI fire through InArc instead
of the old hardcoded 0.99 dot-product test against a live Unity transform.
Settings.cs drops AgentFiringMinDot, which was declared and read by
nothing.

docs/fire-control-cut.md, Cut 1.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Assets/Scripts/Gameplay/EntityInstance.cs

@@ -511,11 +511,6 @@ public class EntityInstance : MonoBehaviour
             x.Value.material.SetFloat("_Emission", Entity.ItemManager.GameplaySettings.TemperatureEmissionCurve.Evaluate(x.Key.RadiatorTemperature));
         }
 
-        foreach (var x in Barrels)
-        {
-            Entity.HardpointTransforms[x.Key] = (x.Value[0].position.ToCultMath(), x.Value[0].forward.ToCultMath());
-        }
-
         LookAtPoint.position = transform.position + Entity.LookDirection.ToUnity() * 
             (Entity.Target.Value != null ? max(Entity.TargetRange,Entity.ItemManager.GameplaySettings.ConvergenceMinimumDistance) : 10000);
         LocalSpace.localPosition = transform.position = Entity.Position.ToUnity();