Soul layer: imprints, warmth echoes, and consequences

Ports the Unity POC soul systems into the sim:
- Warmth echoes: villagers remember who fed them (+0.15) and who turned
  them away (-0.25). Ask-for-food targeting runs on memory, not
  omniscience; the remembered-cold are not asked. Echoes fade daily.
- Refusing the hungry while holding food marks the refuser (others-regard
  debris) and is logged; empty-handed is not refusal.
- Harvesting below the 50% commons line marks the taker per unit taken.
- Soul-to-soul atmospheric pressure (SoulFieldSystem port): encased souls
  darken nearby atmospheres, clear souls lighten them.
- Debris costs biologically: nourishment drains faster and meals restore
  less as the soul encases.
- Instrumentation: avg_debris + refusals in daily stats; per-villager
  nourish/health/debris; refusals in the contact log; map dots dim with
  encasement.

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

scripts/GameManager.cs

@@ -96,6 +96,38 @@ public partial class GameManager : Node2D
         }
     }
 
+    /// <summary>
+    /// Soul-to-soul atmospheric pressure (ported from the Unity POC's
+    /// SoulFieldSystem): souls in proximity press on each other's
+    /// atmospheres. An encased soul darkens the room; a clear soul makes
+    /// it slightly easier for everyone near them to radiate. Both
+    /// directions apply; the net effect depends on relative debris.
+    /// </summary>
+    private void ApplySoulPressure()
+    {
+        const float radius = 8f;
+        const float strength = 0.00004f;
+
+        for (int i = 0; i < Npcs.Count; i++)
+        {
+            for (int j = i + 1; j < Npcs.Count; j++)
+            {
+                var a = Npcs[i];
+                var b = Npcs[j];
+                float dist = a.Position.DistanceTo(b.Position);
+                if (dist > radius) continue;
+
+                float falloff = 1f - dist / radius;
+
+                float fromA = Mathf.Lerp(-strength, strength, a.Imprint.Total) * falloff;
+                b.Imprint.ExternalPerception = Mathf.Clamp(b.Imprint.ExternalPerception + fromA, 0f, 1f);
+
+                float fromB = Mathf.Lerp(-strength, strength, b.Imprint.Total) * falloff;
+                a.Imprint.ExternalPerception = Mathf.Clamp(a.Imprint.ExternalPerception + fromB, 0f, 1f);
+            }
+        }
+    }
+
     /// <summary>Where the community's feet actually are — new communal
     /// buildings are founded here, not at a scripted town center.</summary>
     public Vector2 CommunityCentroid()
@@ -113,11 +145,15 @@ public partial class GameManager : Node2D
         foreach (var npc in Npcs)
             npc.Tick(World, this);
 
+        ApplySoulPressure();
+
         if (TotalTicks % 1440 == 0)
         {
             World.RegenerateDaily(SeasonFoodMult, SeasonWoodMult);
             foreach (var building in Buildings)
                 building.DailyUpkeep();
+            foreach (var npc in Npcs)
+                npc.FadeEchoes(0.005f);
             StatsLogger.LogDay(this);
             if (Day % 10 == 0)
                 GD.Print($"[WorldSim] Day {Day} complete.");