Check building access on every vendor production action

ItemProductionMsgHandler trusted the client to send production, recycle,
junk, deposit, price and take requests only from an open management
window. It now applies the window's own rule (owner, guild leader or IC,
or building friends) before any action.

Value changes: none for players who can open the window; others are
silently ignored.

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

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

@@ -62,6 +62,12 @@ public class ItemProductionMsgHandler extends AbstractClientMsgHandler {
         if (vendor == null)
             return true;
 
+        // Same access rule as opening the vendor's management window (OrderNPCMsgHandler); never trust the client
+
+        if (!BuildingManager.PlayerCanControlNotOwner(vendor.getBuilding(), player)
+                && !BuildingManager.playerCanManage(player, vendor.getBuilding()))
+            return true;
+
         // Process Request
 
         switch (msg.actionType) {