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

src/relay_chn_ctl_multi.c

@@ -38,10 +38,8 @@ esp_err_t relay_chn_ctl_init(relay_chn_output_t *outputs, relay_chn_run_info_t *
         uint16_t run_limit_sec = CONFIG_RELAY_CHN_RUN_LIMIT_DEFAULT_SEC;
 #if CONFIG_RELAY_CHN_ENABLE_NVS
         // Load run limit value from NVS
-        ret = relay_chn_nvs_get_run_limit(chn_ctl->id, &run_limit_sec);
-        if (ret != ESP_OK && ret != ESP_ERR_NVS_NOT_FOUND) {
-            ESP_LOGE(TAG, "Failed to load run limit from NVS for channel %d with error: %s", i, esp_err_to_name(ret));
-        }
+        ret = relay_chn_nvs_get_run_limit(chn_ctl->id, &run_limit_sec, CONFIG_RELAY_CHN_RUN_LIMIT_DEFAULT_SEC);
+        ESP_RETURN_ON_ERROR(ret, TAG, "Failed to load run limit from NVS for #%d with error: %s", i, esp_err_to_name(ret));
 #endif
         chn_ctl->run_limit_sec = run_limit_sec;
         ret = relay_chn_init_run_limit_timer(chn_ctl);