Enhance NVS module with a dedicated background task

- Implemented a dedicated background task to decouple long-running code from the main application task.
- Improved the NVS commit code logic, especially for batch writes to minimize flash wear.
- Updated NVS functions to support asynchronous writes and synchronous reads.
- Added default value parameters to `get` functions for better usability.
- Improved error handling and logging in NVS operations.
- Refactored related code in multiple source files to accommodate these changes.

Refs #1085, #1096 and closes #1098

private_include/relay_chn_nvs.h

@@ -32,6 +32,10 @@ esp_err_t relay_chn_nvs_init(void);
  *
  * @param[in] ch Channel number.
  * @param[in] direction Direction to store.
+ * 
+ * @note This operation is asynchronous. The value is queued to be written
+ *       by a background task. A subsequent `get` call may not immediately
+ *       reflect the new value.
  * @return ESP_OK on success, error code otherwise.
  */
 esp_err_t relay_chn_nvs_set_direction(uint8_t ch, relay_chn_direction_t direction);
@@ -41,16 +45,21 @@ esp_err_t relay_chn_nvs_set_direction(uint8_t ch, relay_chn_direction_t directio
  *
  * @param[in] ch Channel number.
  * @param[out] direction Pointer to store retrieved direction.
+ * @param[in] default_val Default value to use if not found in NVS.
  * @return ESP_OK on success, error code otherwise.
  */
-esp_err_t relay_chn_nvs_get_direction(uint8_t ch, relay_chn_direction_t *direction);
+esp_err_t relay_chn_nvs_get_direction(uint8_t ch, relay_chn_direction_t *direction, relay_chn_direction_t default_val);
 
 #if CONFIG_RELAY_CHN_ENABLE_RUN_LIMIT
 /**
  * @brief Store relay channel run limit in NVS.
  *
  * @param[in] ch Channel number.
- * @param[in] direction Run limit value to store.
+ * @param[in] limit_sec Run limit value to store.
+ * 
+ * @note This operation is asynchronous. The value is queued to be written
+ *       by a background task. A subsequent `get` call may not immediately
+ *       reflect the new value.
  * @return ESP_OK on success, error code otherwise.
  */
 esp_err_t relay_chn_nvs_set_run_limit(uint8_t ch, uint16_t limit_sec);
@@ -59,10 +68,11 @@ esp_err_t relay_chn_nvs_set_run_limit(uint8_t ch, uint16_t limit_sec);
  * @brief Retrieve relay channel run limit from NVS.
  *
  * @param[in] ch Channel number.
- * @param[out] direction Pointer to store retrieved run limit value.
+ * @param[out] limit_sec Pointer to store retrieved run limit value.
+ * @param[in] default_val Default value to use if not found in NVS.
  * @return ESP_OK on success, error code otherwise.
  */
-esp_err_t relay_chn_nvs_get_run_limit(uint8_t ch, uint16_t *limit_sec);
+esp_err_t relay_chn_nvs_get_run_limit(uint8_t ch, uint16_t *limit_sec, uint16_t default_val);
 #endif // CONFIG_RELAY_CHN_ENABLE_RUN_LIMIT == 1
 
 #if CONFIG_RELAY_CHN_ENABLE_TILTING
@@ -71,6 +81,10 @@ esp_err_t relay_chn_nvs_get_run_limit(uint8_t ch, uint16_t *limit_sec);
  *
  * @param[in] ch Channel number.
  * @param[in] sensitivity Sensitivity value to store.
+ * 
+ * @note This operation is asynchronous. The value is queued to be written
+ *       by a background task. A subsequent `get` call may not immediately
+ *       reflect the new value.
  * @return ESP_OK on success, error code otherwise.
  */
 esp_err_t relay_chn_nvs_set_tilt_sensitivity(uint8_t ch, uint8_t sensitivity);
@@ -80,15 +94,20 @@ esp_err_t relay_chn_nvs_set_tilt_sensitivity(uint8_t ch, uint8_t sensitivity);
  *
  * @param[in] ch Channel number.
  * @param[out] sensitivity Pointer to store retrieved sensitivity.
+ * @param[in] default_val Default value to use if not found in NVS.
  * @return ESP_OK on success, error code otherwise.
  */
-esp_err_t relay_chn_nvs_get_tilt_sensitivity(uint8_t ch, uint8_t *sensitivity);
+esp_err_t relay_chn_nvs_get_tilt_sensitivity(uint8_t ch, uint8_t *sensitivity, uint8_t default_val);
 
 /**
  * @brief Store tilt counters in NVS.
  *
  * @param[in] ch Channel number.
  * @param[in] tilt_count Tilt count value.
+ * 
+ * @note This operation is asynchronous. The value is queued to be written
+ *       by a background task. A subsequent `get` call may not immediately
+ *       reflect the new value.
  * @return ESP_OK on success, error code otherwise.
  */
 esp_err_t relay_chn_nvs_set_tilt_count(uint8_t ch, uint16_t tilt_count);
@@ -98,15 +117,17 @@ esp_err_t relay_chn_nvs_set_tilt_count(uint8_t ch, uint16_t tilt_count);
  *
  * @param[in] ch Channel number.
  * @param[out] tilt_count Pointer to store tilt count.
+ * @param[in] default_val Default value to use if not found in NVS.
  * @return ESP_OK on success, error code otherwise.
  */
-esp_err_t relay_chn_nvs_get_tilt_count(uint8_t ch, uint16_t *tilt_count);
+esp_err_t relay_chn_nvs_get_tilt_count(uint8_t ch, uint16_t *tilt_count, uint16_t default_val);
 #endif // CONFIG_RELAY_CHN_ENABLE_TILTING
 
 /**
  * @brief Erase all keys in the NVS namespace.
  *
  * This function will erase all key-value pairs in the NVS namespace used by relay channels.
+ * It will also flush all pending operations in the queue.
  *
  * @return ESP_OK on success, error code otherwise.
  */
@@ -114,10 +135,8 @@ esp_err_t relay_chn_nvs_erase_all(void);
 
 /**
  * @brief Deinitialize NVS storage for relay channels.
- *
- * @return ESP_OK on success, error code otherwise.
  */
-esp_err_t relay_chn_nvs_deinit(void);
+void relay_chn_nvs_deinit(void);
 
 #ifdef __cplusplus
 }