Organic construction v2: three verified fixes, one open problem

Fixes (headless-verified): homes founded at the habitual sleeping spot
within reach of the community (not at distant stone mines); night sends
everyone to bed so beds are used and rough nights actually occur; a bed
must exist at arrival - floor-sleepers at full shelters now count as
unsheltered. Diagnostics added: incomplete_sites stat column, founding
logs.

Open (documented in FINDINGS.md, paused by request): the loop builds
forward but cannot rebuild after loss - winter crises ruin shelters and
recovery stalls (4 foundings in 240 days, no granary after two famines).

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

scripts/GameManager.cs

@@ -117,12 +117,14 @@ public partial class GameManager : Node2D
         }
     }
 
-    /// <summary>How many villagers are currently sleeping at this shelter.</summary>
-    public int RestingOccupancy(Building b)
+    /// <summary>How many villagers (other than <paramref name="except"/>)
+    /// are currently sleeping at this shelter.</summary>
+    public int RestingOccupancy(Building b, Npc? except = null)
     {
         int count = 0;
         foreach (var npc in Npcs)
-            if (npc.State == NpcState.Resting && npc.Position.DistanceTo(b.Site) <= 2.5f)
+            if (npc != except && npc.State == NpcState.Resting &&
+                npc.Position.DistanceTo(b.Site) <= 2.5f)
                 count++;
         return count;
     }