Refactor to split .h into .h and .cpp pair

src/data/config_store.h

@@ -0,0 +1,12 @@
+// Copyright (C) 2026 Hector van der Aa <hector@h3cx.dev>
+// Copyright (C) 2026 Association Exergie <association.exergie@gmail.com>
+// SPDX-License-Identifier: GPL-3.0-or-later
+#pragma once
+
+#include "custom_types.h"
+#include <EEPROM.h>
+
+extern volatile vehicle_config config_global;
+
+void config_global_read(vehicle_config& out);
+void config_global_write(const vehicle_config& in);