Keep receiver LoRa in continuous RX

- Add lora_receive_continuous() helper and use it after init and TX (ACK/time sync)

- Ensure receiver returns to RX immediately after lora_send

- Document continuous RX behavior in README

README.md

@@ -133,6 +133,8 @@ void receiver_loop() {
 }
 ```
 
+Receiver keeps the SX1276 in continuous RX, re-entering RX after any transmit (ACK or time sync).
+
 **Key receiver functions**:
 ```cpp
 bool lora_receive(LoraPacket &pkt, uint32_t timeout_ms);

include/lora_transport.h

@@ -21,5 +21,6 @@ bool lora_send(const LoraPacket &pkt);
 bool lora_receive(LoraPacket &pkt, uint32_t timeout_ms);
 void lora_idle();
 void lora_sleep();
+void lora_receive_continuous();
 bool lora_receive_window(LoraPacket &pkt, uint32_t timeout_ms);
 uint32_t lora_airtime_ms(size_t packet_len);

src/lora_transport.cpp

@@ -118,6 +118,10 @@ void lora_sleep() {
   LoRa.sleep();
 }
 
+void lora_receive_continuous() {
+  LoRa.receive();
+}
+
 bool lora_receive_window(LoraPacket &pkt, uint32_t timeout_ms) {
   if (timeout_ms == 0) {
     return false;

src/main.cpp

@@ -431,6 +431,7 @@ static void send_batch_ack(uint16_t batch_id, uint16_t sender_id) {
   write_u16_le(&ack.payload[2], sender_id);
   write_u16_le(&ack.payload[4], g_short_id);
   lora_send(ack);
+  lora_receive_continuous();
 }
 
 static bool prepare_inflight_from_queue() {
@@ -651,6 +652,7 @@ void setup() {
     update_battery_cache();
   } else {
     power_receiver_init();
+    lora_receive_continuous();
     pinMode(PIN_ROLE, INPUT); // release pulldown before SD uses GPIO14 as SCK
     sd_logger_init();
     wifi_manager_init();

src/time_manager.cpp

@@ -83,7 +83,11 @@ bool time_send_timesync(uint16_t device_id_short) {
   pkt.payload_type = PayloadType::TimeSync;
   pkt.payload_len = compressed_len;
   memcpy(pkt.payload, compressed, compressed_len);
-  return lora_send(pkt);
+  bool ok = lora_send(pkt);
+  if (ok) {
+    lora_receive_continuous();
+  }
+  return ok;
 }
 
 bool time_handle_timesync_payload(const uint8_t *payload, size_t len) {