Add IEC62056 parsing, OLED timing, and batch LoRa send

src/power_manager.cpp

@@ -47,6 +47,14 @@ uint8_t battery_percent_from_voltage(float voltage_v) {
   return static_cast<uint8_t>(pct + 0.5f);
 }
 
+void light_sleep_ms(uint32_t ms) {
+  if (ms == 0) {
+    return;
+  }
+  esp_sleep_enable_timer_wakeup(static_cast<uint64_t>(ms) * 1000ULL);
+  esp_light_sleep_start();
+}
+
 void go_to_deep_sleep(uint32_t seconds) {
   esp_sleep_enable_timer_wakeup(static_cast<uint64_t>(seconds) * 1000000ULL);
   esp_deep_sleep_start();