Added battery module, cal factor refresh bug

src/modules/battery/battery.h

@@ -2,8 +2,10 @@
 // Copyright (C) 2026 Association Exergie <association.exergie@gmail.com>
 // SPDX-License-Identifier: GPL-3.0-or-later
 #pragma once
-
+#define VBAT_PIN A3
 #include "base/module_base.h"
+#include "base/ring_buffer.h"
+#include "custom_types.h"
 #include "modules/logger/system_logger.h"
 #include <Arduino.h>
 
@@ -12,10 +14,17 @@ class battery : public module_base {
 private:
   system_logger *_logger;
   ring_buffer<Task, 16> _queue;
+  double _vbat = 0;
+  double _cal = 0;
+  unsigned long _update_interval = 1000;
+  unsigned long _last_read = 0;
+  int calibrate(const Task& task);
 
 public:
   int push(const Task &task) override;
   battery();
   battery(system_logger *logger);
   ~battery();
+  int init();
+  int loop(unsigned long timeout_ms = 500);
 };