Add run limit feature for relay channels with NVS support

- Introduced configuration options for enabling run limits in Kconfig.
- Added APIs to get and set run limits for individual relay channels.
- Implemented run limit timer functionality to automatically stop channels.
- Updated NVS handling to store and retrieve run limit values.
- Enhanced documentation in README and code comments to reflect new feature.

Closes #1080

src/relay_chn_nvs.c

@@ -8,6 +8,9 @@
 #include "relay_chn_nvs.h"
 
 #define RELAY_CHN_KEY_DIR          "dir"    /*!< Direction key */
+#if RELAY_CHN_ENABLE_RUN_LIMIT == 1
+#define RELAY_CHN_KEY_RLIM(ch)  "rlim_%d"   /*!< Run limit key */
+#endif
 #ifdef RELAY_CHN_ENABLE_TILTING
 #define RELAY_CHN_KEY_TSENS(ch) "tsens_%d"  /*!< Tilt sensitivity key */
 #define RELAY_CHN_KEY_TCNT(ch)  "tcnt_%d"   /*!< Tilt count key */
@@ -69,6 +72,22 @@ esp_err_t relay_chn_nvs_get_direction(uint8_t ch, relay_chn_direction_t *directi
     return ESP_OK;
 }
 
+#if RELAY_CHN_ENABLE_RUN_LIMIT == 1
+esp_err_t relay_chn_nvs_set_run_limit(uint8_t ch, uint16_t time_sec)
+{
+    esp_err_t ret = nvs_set_u16(relay_chn_nvs, RELAY_CHN_KEY_RLIM(ch), time_sec);
+    ESP_RETURN_ON_ERROR(ret, TAG, "Failed to set run limit for channel %d", ch);
+    return nvs_commit(relay_chn_nvs);
+}
+
+esp_err_t relay_chn_nvs_get_run_limit(uint8_t ch, uint16_t *time_sec)
+{
+    ESP_RETURN_ON_FALSE(time_sec != NULL, ESP_ERR_INVALID_ARG, TAG, "Run limit value pointer is NULL");
+
+    return nvs_get_u16(relay_chn_nvs, RELAY_CHN_KEY_RLIM(ch), time_sec);
+}
+#endif // RELAY_CHN_ENABLE_RUN_LIMIT == 1
+
 #ifdef RELAY_CHN_ENABLE_TILTING
 esp_err_t relay_chn_nvs_set_tilt_sensitivity(uint8_t ch, uint8_t sensitivity)
 {