diag: add verbose network listener logging to trace command delivery

Manager logs: listener start, every modem_message received, channel
match/mismatch, command acceptance count, handler result.
Client logs: every sendToMaster call with type and commandId.

inventoryClient.lua

@@ -105,10 +105,14 @@ end
 -------------------------------------------------
 
 local function sendToMaster(message)
-    if not networkModem then return end
+    if not networkModem then
+        log.warn("NET", "sendToMaster: no modem, dropping %s", tostring(message.type))
+        return
+    end
     if not message.commandId then
         message.commandId = newCommandId()
     end
+    log.info("NET", "TX -> ch %d: type=%s cmdId=%s", ORDER_CHANNEL, tostring(message.type), tostring(message.commandId))
     networkModem.transmit(ORDER_CHANNEL, CLIENT_CHANNEL, message)
 end