fix: client crash from barrel task early return in waitForAny

Same bug as the manager: CLIENT_BARREL_NAME == '' caused return
inside parallel.waitForAny, killing all tasks instantly.
Replace with infinite sleep when barrel is unconfigured.

inventoryClient.lua

@@ -1395,7 +1395,9 @@ local function main()
 
         -- Task 5: Client barrel auto-sort (sends to master only when barrel has items)
         function()
-            if CLIENT_BARREL_NAME == "" then return end
+            if CLIENT_BARREL_NAME == "" then
+                while true do sleep(3600) end
+            end
             log.info("INIT", "Client barrel: %s", CLIENT_BARREL_NAME)
             while true do
                 local barrel = peripheral.wrap(CLIENT_BARREL_NAME)