Refactor LoRa protocol to batch+ack with ACK-based time bootstrap

include/time_manager.h

@@ -1,17 +1,11 @@
 #pragma once
 
 #include <Arduino.h>
-#include "lora_transport.h"
 
 void time_receiver_init(const char *ntp_server_1, const char *ntp_server_2);
 uint32_t time_get_utc();
 bool time_is_synced();
 void time_set_utc(uint32_t epoch);
-bool time_send_timesync(uint16_t device_id_short);
-bool time_handle_timesync_payload(const uint8_t *payload, size_t len);
 void time_get_local_hhmm(char *out, size_t out_len);
-void time_rtc_init();
-bool time_try_load_from_rtc();
-bool time_rtc_present();
 uint32_t time_get_last_sync_utc();
 uint32_t time_get_last_sync_age_sec();