Skip the strongbox of NPC buildings when forging and recycling

Forge submit and vendor recycle took gold from, or refunded gold to, the
vendor building's strongbox with no protection check. NPC-city vendors
could roll on the static building's 2000 gold. Vendor buy, repair and train
already skip NPC buildings.

Value changes: forging at a vendor in a protection-NPC building now fails
with popup 58; recycling there does nothing.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/engine/gameManager/ForgeManager.java

@@ -131,6 +131,11 @@ public enum ForgeManager implements Runnable {
         if (city == null)
             return 58; //58: The formula is beyond the means of this facility
 
+        // NPC buildings have no strongbox to pay from, as in vendor buy, repair and train
+
+        if (workOrder.vendor.building.getProtectionState() == mbEnums.ProtectionState.NPC)
+            return 58;
+
         // Concurrency is rightly managed by same lock as warehouse
 
         city.transactionLock.writeLock().lock();

src/engine/net/client/handlers/ItemProductionMsgHandler.java

@@ -299,6 +299,11 @@ public class ItemProductionMsgHandler extends AbstractClientMsgHandler {
         if (vendor.getBuilding() == null)
             return;
 
+        // NPC buildings have no strongbox to refund into
+
+        if (vendor.getBuilding().getProtectionState() == mbEnums.ProtectionState.NPC)
+            return;
+
         PlayerCharacter player = origin.getPlayerCharacter();
 
         if (player == null)