Add single channel mode feature.

The addition of a single-channel mode implied further modularisation of the component. This commit has broken the component down into the following modules to avoid a huge single source file and to make unit testing easier.

The modules:

- Separation of public and private code
- *types and *defs
- public relay_chn API
- *adapter
- *output
- *run_info
- *core
- *ctl (control)
- *tilt

Closes #957.

private_include/relay_chn_output.h

@@ -0,0 +1,113 @@
+/*
+ * SPDX-FileCopyrightText: 2025 Kozmotronik Tech
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ * Abstraction layer for controlling relay channel outputs. This is the layer
+ * that interacts with the GPIO pins to control the relay channels.
+ */
+
+#pragma once
+
+#include <stdint.h>
+#include "esp_err.h"
+#include "relay_chn_priv_types.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief Initialize relay channel outputs.
+ *
+ * Maps relay channels to GPIO pins and prepares them for operation.
+ *
+ * @param[in] gpio_map Array of GPIO pin numbers for each relay channel.
+ * @param[in] gpio_count Number of GPIO pins (relay channels).
+ * 
+ * @return ESP_OK on success, error code otherwise.
+ */
+esp_err_t relay_chn_output_init(const uint8_t* gpio_map, uint8_t gpio_count);
+
+/**
+ * @brief Deinitialize relay channel outputs.
+ *
+ * Releases resources and resets GPIO pins used for relay channels.
+ */
+void relay_chn_output_deinit(void);
+
+#if RELAY_CHN_COUNT > 1
+/**
+ * @brief Get the relay channel output object for a specific channel.
+ *
+ * @param[in] chn_id Channel ID.
+ * 
+ * @return Pointer to relay channel output object, or NULL if invalid.
+ */
+relay_chn_output_t *relay_chn_output_get(uint8_t chn_id);
+
+/**
+ * @brief Get all relay channel output objects.
+ *
+ * @return Pointer to array of relay channel output objects.
+ */
+relay_chn_output_t *relay_chn_output_get_all(void);
+#else
+/**
+ * @brief Get the relay channel output object.
+ *
+ * @return Pointer to relay channel output object.
+ */
+relay_chn_output_t *relay_chn_output_get(void);
+#endif // RELAY_CHN_COUNT > 1
+
+/**
+ * @brief Stop the relay channel output.
+ *
+ * Sets the relay channel to the stop state.
+ *
+ * @param[in] output Pointer to relay channel output object.
+ * 
+ * @return ESP_OK on success, error code otherwise.
+ */
+esp_err_t relay_chn_output_stop(relay_chn_output_t *output);
+
+/**
+ * @brief Set relay channel output to forward direction.
+ *
+ * @param[in] output Pointer to relay channel output object.
+ * 
+ * @return ESP_OK on success, error code otherwise.
+ */
+esp_err_t relay_chn_output_forward(relay_chn_output_t *output);
+
+/**
+ * @brief Set relay channel output to reverse direction.
+ *
+ * @param[in] output Pointer to relay channel output object.
+ * 
+ * @return ESP_OK on success, error code otherwise.
+ */
+esp_err_t relay_chn_output_reverse(relay_chn_output_t *output);
+
+/**
+ * @brief Flip the direction of the relay channel output.
+ *
+ * Changes the direction from forward to reverse or vice versa.
+ *
+ * @param[in] output Pointer to relay channel output object.
+ */
+void relay_chn_output_flip(relay_chn_output_t *output);
+
+/**
+ * @brief Get the current direction of the relay channel output.
+ *
+ * @param[in] output Pointer to relay channel output object.
+ * 
+ * @return Current direction of the relay channel.
+ */
+relay_chn_direction_t relay_chn_output_get_direction(relay_chn_output_t *output);
+
+#ifdef __cplusplus
+}
+#endif