feat: Integrate VND7050AJ driver and enhance gateway settings

This commit introduces the VND7050AJ driver as a new submodule and integrates it into the project.

Key changes include:
- Added  as a git submodule.
- Enhanced the gateway application () with LittleFS and the settings subsystem.
  - Implemented new shell commands (, , ) for managing custom settings.
  - Added functionality to compact the settings file.
- Updated  to include new library dependencies and log  return code.
- Adjusted include paths for  in relevant files.
Signed-off-by: Eduard Iten <eduard@iten.pro>

software/include/lib/vnd7050aj.h

@@ -0,0 +1,74 @@
+/*
+ * Copyright (c) 2025, Eduard Iten
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#ifndef ZEPHYR_INCLUDE_DRIVERS_MISC_VND7050AJ_H_
+#define ZEPHYR_INCLUDE_DRIVERS_MISC_VND7050AJ_H_
+
+#include <zephyr/device.h>
+#include <zephyr/kernel.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief Channel identifiers for the VND7050AJ.
+ */
+#define VND7050AJ_CHANNEL_0 0
+#define VND7050AJ_CHANNEL_1 1
+
+/**
+ * @brief Sets the state of a specific output channel.
+ *
+ * @param dev Pointer to the device structure for the driver instance.
+ * @param channel The channel to control (VND7050AJ_CHANNEL_0 or VND7050AJ_CHANNEL_1).
+ * @param state The desired state (true for ON, false for OFF).
+ * @return 0 on success, negative error code on failure.
+ */
+int vnd7050aj_set_output_state(const struct device *dev, uint8_t channel, bool state);
+
+/**
+ * @brief Reads the load current for a specific channel.
+ *
+ * @param dev Pointer to the device structure for the driver instance.
+ * @param channel The channel to measure (VND7050AJ_CHANNEL_0 or VND7050AJ_CHANNEL_1).
+ * @param[out] current_ma Pointer to store the measured current in milliamperes (mA).
+ * @return 0 on success, negative error code on failure.
+ */
+int vnd7050aj_read_load_current(const struct device *dev, uint8_t channel, int32_t *current_ma);
+
+/**
+ * @brief Reads the VCC supply voltage.
+ *
+ * @param dev Pointer to the device structure for the driver instance.
+ * @param[out] voltage_mv Pointer to store the measured voltage in millivolts (mV).
+ * @return 0 on success, negative error code on failure.
+ */
+int vnd7050aj_read_supply_voltage(const struct device *dev, int32_t *voltage_mv);
+
+/**
+ * @brief Reads the internal chip temperature.
+ *
+ * @param dev Pointer to the device structure for the driver instance.
+ * @param[out] temp_c Pointer to store the measured temperature in degrees Celsius (°C).
+ * @return 0 on success, negative error code on failure.
+ */
+int vnd7050aj_read_chip_temp(const struct device *dev, int32_t *temp_c);
+
+/**
+ * @brief Resets a latched fault condition.
+ *
+ * This function sends a low pulse to the FaultRST pin.
+ *
+ * @param dev Pointer to the device structure for the driver instance.
+ * @return 0 on success, negative error code on failure.
+ */
+int vnd7050aj_reset_fault(const struct device *dev);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* ZEPHYR_INCLUDE_DRIVERS_MISC_VND7050AJ_H_ */