Fix run-7 stone-lock collapse: construction outranks founding

Priority inversion fix: the homeless-gather-stone rule preempted all
communal work, so once everyone was homeless the town gathered stone
forever while half-built walls waited for wood that never came. Now
construction sites are first among works, homeless stone-gathering and
founding defer while any shelter is under construction, and granaries
require hunger memory + surplus (no more day-5 granary sprawl).
Run 7 logged in FINDINGS.md: in a needs-driven economy, priority
ordering is the constitution.

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

scripts/NPC.cs

@@ -210,17 +210,18 @@ public class Npc
             // town's hearths. (Helping a neighbor town is a later, deliberate
             // system, not an accident of the work queue.)
 
-            // 1.5. A roof of your own: kept sleeping outside? Gather stone.
-            // (The founding itself happens in TickBuilding once you're
-            // carrying enough — need drives supply drives construction.)
-            if (_unshelteredRests >= 3)
-                return MaterialKind.Stone;
-
-            // 2. Construction sites.
+            // 2. Construction sites — always first among works. Finishing
+            // the walls of a half-built shelter beats founding another
+            // foundation (the day-40 collapse taught us this one).
             foreach (var b in gm.Buildings)
                 if (b.Town == HomeTown && !b.IsComplete && b.NeededMaterial is MaterialKind needed)
                     return needed;
 
+            // 2.5. Kept sleeping outside, and nothing in town is being
+            // built: gather stone to found a roof of your own.
+            if (_unshelteredRests >= 3 && !TownHasIncompleteShelter(gm))
+                return MaterialKind.Stone;
+
             // 3. Firewood for shelters running low.
             foreach (var b in gm.Buildings)
                 if (b.Town == HomeTown && b.WantsUpkeepWood)
@@ -252,6 +253,15 @@ public class Npc
         return best;
     }
 
+    /// <summary>True if this town has a shelter currently under construction.</summary>
+    private bool TownHasIncompleteShelter(GameManager gm)
+    {
+        foreach (var b in gm.Buildings)
+            if (b.Town == HomeTown && b.Kind == BuildingKind.Shelter && !b.IsComplete && !b.IsRuined)
+                return true;
+        return false;
+    }
+
     /// <summary>True if this town has any granary (built or building) with room.</summary>
     private bool TownHasFoodStorage(GameManager gm)
     {
@@ -478,10 +488,11 @@ public class Npc
                 gm.Buildings.Add(site);
                 _unshelteredRests = 0;
             }
-            // Carrying a surplus with nowhere to put it → the barn goes
-            // where the harvest is. A second granary appears when the
-            // first fills; storage scales with abundance.
-            else if (Inventory.TryGetValue(MaterialKind.Food, out float surplus) && surplus > 8f)
+            // Hunger remembered + a surplus with nowhere to put it → the
+            // barn goes where the harvest is. Founded by scarcity survived,
+            // not by abundance alone; another appears only when this fills.
+            else if (_hungerMemory &&
+                     Inventory.TryGetValue(MaterialKind.Food, out float surplus) && surplus > 8f)
             {
                 site = Building.NewGranary(Position + jitter);
                 site.Town = HomeTown;