Add centralized LEDManager for configurable LED behavior

Adds a LEDManager class (src/helpers/ui/LEDManager.h) that centralizes
all LED control into one component with begin()/loop() lifecycle and
per-pin active-HIGH/LOW polarity support.

LED settings are exposed as custom vars (led.status, led.activity)
accessible via companion radio binary protocol, CLI set/get commands,
and the SensorManager settings interface.

Status LED modes: off, boot-30s, slow blink (200ms/4s), always on.
Activity LED modes: off, BLE only, LoRa TX only, BLE + LoRa TX.

Integrated into 23 board variants, replacing scattered hardcoded
digitalWrite calls in onBeforeTransmit/onAfterTransmit/powerOff.

examples/companion_radio/main.cpp

@@ -1,5 +1,6 @@
 #include <Arduino.h>   // needed for PlatformIO
 #include <Mesh.h>
+#include <helpers/ui/LEDManager.h>
 #include "MyMesh.h"
 
 // Believe it or not, this std C function is busted on some platforms!
@@ -155,6 +156,7 @@ void setup() {
 #else
   serial_interface.begin(Serial);
 #endif
+  if (board.ledManager) serial_interface.setLEDManager(board.ledManager);
   the_mesh.startInterface(serial_interface);
 #elif defined(RP2040_PLATFORM)
   LittleFS.begin();
@@ -212,6 +214,7 @@ void setup() {
 #endif
 
   sensors.begin();
+  if (board.ledManager) sensors.setLEDManager(board.ledManager);
 
 #ifdef DISPLAY_CLASS
   ui_task.begin(disp, &sensors, the_mesh.getNodePrefs());  // still want to pass this in as dependency, as prefs might be moved
@@ -221,6 +224,7 @@ void setup() {
 void loop() {
   the_mesh.loop();
   sensors.loop();
+  if (board.ledManager) board.ledManager->loop();
 #ifdef DISPLAY_CLASS
   ui_task.loop();
 #endif

examples/kiss_modem/main.cpp

@@ -83,6 +83,7 @@ void setup() {
   loadOrCreateIdentity();
 
   sensors.begin();
+  if (board.ledManager) sensors.setLEDManager(board.ledManager);
 
 #if defined(KISS_UART_RX) && defined(KISS_UART_TX)
 #if defined(ESP32)
@@ -143,4 +144,5 @@ void loop() {
     next_noise_floor_calib_ms = millis();
   }
   radio_driver.loop();
+  if (board.ledManager) board.ledManager->loop();
 }

examples/simple_repeater/main.cpp

@@ -1,5 +1,6 @@
 #include <Arduino.h>   // needed for PlatformIO
 #include <Mesh.h>
+#include <helpers/ui/LEDManager.h>
 
 #include "MyMesh.h"
 
@@ -92,6 +93,7 @@ void setup() {
   command[0] = 0;
 
   sensors.begin();
+  if (board.ledManager) sensors.setLEDManager(board.ledManager);
 
   the_mesh.begin(fs);
 
@@ -149,6 +151,7 @@ void loop() {
 
   the_mesh.loop();
   sensors.loop();
+  if (board.ledManager) board.ledManager->loop();
 #ifdef DISPLAY_CLASS
   ui_task.loop();
 #endif

examples/simple_room_server/main.cpp

@@ -1,5 +1,6 @@
 #include <Arduino.h>   // needed for PlatformIO
 #include <Mesh.h>
+#include <helpers/ui/LEDManager.h>
 
 #include "MyMesh.h"
 
@@ -69,6 +70,7 @@ void setup() {
   command[0] = 0;
 
   sensors.begin();
+  if (board.ledManager) sensors.setLEDManager(board.ledManager);
 
   the_mesh.begin(fs);
 
@@ -109,6 +111,7 @@ void loop() {
 
   the_mesh.loop();
   sensors.loop();
+  if (board.ledManager) board.ledManager->loop();
 #ifdef DISPLAY_CLASS
   ui_task.loop();
 #endif

examples/simple_sensor/main.cpp

@@ -103,6 +103,7 @@ void setup() {
   command[0] = 0;
 
   sensors.begin();
+  if (board.ledManager) sensors.setLEDManager(board.ledManager);
 
   the_mesh.begin(fs);
 
@@ -143,6 +144,7 @@ void loop() {
 
   the_mesh.loop();
   sensors.loop();
+  if (board.ledManager) board.ledManager->loop();
 #ifdef DISPLAY_CLASS
   ui_task.loop();
 #endif