Ship contact is a simulation rule: Zone steps Contacts, Unity physics writes no Entity

Contacts.Step exchanges normal velocity between touching hull discs (PostCollisionVelocity moved verbatim
from ShieldManager) and publishes Zone.Contacted; ShieldManager presents it; HullCollider.OnCollisionEnter
and ShieldManager's ship-on-ship branch are deleted. Not yet built or tested (verification follows).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Assets/Scripts/ServerShared/Zone.cs

@@ -54,6 +54,8 @@ public class Zone
     public List<PendingShot> PendingShots = new List<PendingShot>();
     public Subject<ShotOutcome> ShotCommitted = new Subject<ShotOutcome>();
     public Subject<ShotOutcome> ShotResolved = new Subject<ShotOutcome>();
+    // Contacts.Step publishes each hull-on-hull contact it resolves; presentations are the only readers.
+    public Subject<ContactEvent> Contacted = new Subject<ContactEvent>();
     private int _nextShotId;
     public int NextShotId() => ++_nextShotId;
 
@@ -241,6 +243,10 @@ public class Zone
         StepMines(deltaTime);
         StepClouds(deltaTime);
 
+        // Hull contact (cut sim-contact): after every entity has moved and the mines and clouds have taken
+        // their toll, so only hulls still in the zone touch, and before shots resolve against the result.
+        Contacts.Step(this);
+
         // Cut 3: after every entity has had its chance to fire this tick, age and resolve the shots that
         // firing queued. A shot fired this tick with a flight time shorter than CommitHorizon commits and
         // resolves in this same call.