Log ACK transmit and reject cases

- Add debug log for ACK TX with batch/sender/receiver ids
- Log rejected ACKs to help diagnose mismatched ids or batches

src/main.cpp

@@ -497,6 +497,9 @@ static void send_batch_ack(uint16_t batch_id, uint16_t sender_id) {
   write_u16_le(&ack.payload[0], batch_id);
   write_u16_le(&ack.payload[2], sender_id);
   write_u16_le(&ack.payload[4], g_short_id);
+  if (SERIAL_DEBUG_MODE) {
+    serial_debug_printf("ack: tx batch_id=%u sender=%u receiver=%u", batch_id, sender_id, g_short_id);
+  }
   lora_send(ack);
   lora_receive_continuous();
 }
@@ -851,6 +854,9 @@ static void sender_loop() {
         g_last_acked_batch_id = ack_id;
         serial_debug_printf("ack: ok batch_id=%u", ack_id);
         finish_inflight_batch();
+      } else if (SERIAL_DEBUG_MODE) {
+        serial_debug_printf("ack: reject batch_id=%u sender=%u receiver=%u exp_batch=%u exp_sender=%u",
+                            ack_id, ack_sender, ack_receiver, g_last_sent_batch_id, g_short_id);
       }
     }
   }