Town-colored homes, split diagonally for mixed-culture households

Shelters now wear their town's culture color on the map (North cool-blue,
South green, West gold, East red), dimmed by wear; granaries stay green,
ruins dark. And bonds can now cross town lines: usually you pair within
your own people (that's who you're near), but a wanderer who warms to
someone from another town shacks up across cultures - the first quiet
thread of contact between two peoples. When two towns share a roof, the
house is drawn split diagonally, half each culture, visible across the map.

Mechanics: buildings track their top-two resident home-towns (recomputed
with occupancy, throttled to every 30 ticks since it's map-only); the
bonding rule dropped its same-town requirement. A 240-day run produced
126 bonds, 40 of them cross-town (East+North, West+South, all combos),
with populations still balanced - inter-cultural contact without
destabilizing the towns.

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

scripts/NPC.cs

@@ -950,15 +950,20 @@ public class Npc
         nearest = found;
 
         // Consider bonding: an unbonded adult who keeps warm company with a
-        // compatible, unbonded neighbor may pair with them. Same town, real
-        // warmth, both grown — companionship chosen, not assigned.
+        // compatible, unbonded neighbor may pair with them — real warmth,
+        // both grown, companionship chosen not assigned. Town is NOT a
+        // requirement: usually you bond within your own people (that's who
+        // you're near), but a wanderer who warms to someone from another
+        // town can shack up across cultures — the first quiet thread of
+        // contact between two peoples.
         if (!IsBonded && IsAdult && nearest is { IsBonded: false, IsAdult: true } n &&
-            n.HomeTown == HomeTown && Position.DistanceTo(n.Position) < 4f &&
+            Position.DistanceTo(n.Position) < 4f &&
             GetWarmth(n.Name) > 0.4f && n.GetWarmth(Name) > 0.4f)
         {
             Partner = n;
             n.Partner = this;
-            Godot.GD.Print($"[Bond] day {gm.Day}: {Name} and {n.Name} ({HomeTown}) pair up.");
+            string kind = n.HomeTown == HomeTown ? HomeTown : $"{HomeTown}+{n.HomeTown}";
+            Godot.GD.Print($"[Bond] day {gm.Day}: {Name} and {n.Name} ({kind}) pair up.");
         }
         if (nearest != null && Position.DistanceTo(nearest.Position) > 3f)
         {