fix: prevent early return in parallel tasks from killing waitForAny

Task 12 (supply chest) and Task 13 (network) returned immediately
when not configured, which caused parallel.waitForAny to exit and
the entire program to silently stop after cache build.

inventoryManager.lua

@@ -478,7 +478,9 @@ local function main()
 
         -- Task 12: Supply chest (builder / manifest-based stocking)
         function()
-            if cfg.SUPPLY_CHEST == "" or #cfg.SUPPLY_MANIFEST == 0 then return end
+            if cfg.SUPPLY_CHEST == "" or #cfg.SUPPLY_MANIFEST == 0 then
+                while true do sleep(3600) end
+            end
             log.info("SUPPLY", "Stocking %s with %d item types", cfg.SUPPLY_CHEST, #cfg.SUPPLY_MANIFEST)
             while true do
                 pcall(ops.supplyChest)
@@ -488,7 +490,9 @@ local function main()
 
         -- Task 13: Network order/command listener
         function()
-            if not ctx.networkModem then return end
+            if not ctx.networkModem then
+                while true do sleep(3600) end
+            end
             while true do
                 local event, side, channel, replyChannel, message, distance = os.pullEvent("modem_message")
                 if channel == cfg.ORDER_CHANNEL and type(message) == "table" then