Run 12: knowledge system, mortality, and the North's generational soul

SPEC §5 built: three skill domains (forage/woodcraft/masonry) that pay
off and grow by practice; proximity diffusion soul-calibrated by
absorption x teaching-drive; and mortality - the piece that makes
knowledge generational. Elders die (~150-230 days), everything unshared
dies with them, a youth comes of age near knowing nothing. North soul
(absorption 1.6, teaching 0.9) vs South (1.0, 0.3); East teaches no one.

Two findings: (1) headless soaks were contaminated by orphaned child
processes writing later runs' CSVs - fixed with StopAfterDays clean
self-terminate; (2) passive diffusion barely helped - the North's real
culture is the young seeking elders on purpose, so added deliberate
teacher-seeking and youths now cradle beside the wisest elder. North
now leads knowledge at every checkpoint, but a stable town approaches
the ceiling regardless, so teaching is a recovery advantage not an
equilibrium one. The crisis-recovery experiment is the real test, noted
in FINDINGS as next.

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

scripts/Building.cs

@@ -151,9 +151,13 @@ public class Building
             if (!npc.Inventory.TryGetValue(stage.Material, out float have) || have <= 0f)
                 return false;
 
-            float take = Mathf.Min(have, stage.Cost - Delivered);
+            // A practiced mason wastes less: the same materials go further
+            // in skilled hands — and the building is the teacher.
+            float masonry = npc.Know[KnowledgeDomain.Masonry];
+            float take = Mathf.Min(have, (stage.Cost - Delivered) / (1f + masonry * 0.5f));
             npc.Inventory[stage.Material] = have - take;
-            Delivered += take;
+            Delivered += take * (1f + masonry * 0.5f);
+            npc.Know.Gain(KnowledgeDomain.Masonry, 0.002f);
 
             if (Delivered >= stage.Cost)
             {