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

scripts/run_tests.sh

@@ -10,7 +10,7 @@ if [[ -z "$IDF_PATH" ]]; then
 fi
 
 # ==== 2. Valid Modes and Defaults ====
-valid_test_tags=("core" "tilt" "listener" "all" "relay_chn" "nvs")
+valid_test_tags=("core" "tilt" "listener" "all" "relay_chn" "nvs" "run_limit")
 arg_tag="all" # Default to 'all' if no tag specified
 arg_clean=false
 arg_log=false
@@ -24,7 +24,7 @@ print_help() {
     echo "This script builds and runs tests for the relay_chn component using QEMU."
     echo ""
     echo "Arguments:"
-    echo "  -t, --tag [relay_chn|core|tilt|listener|nvs|all]  Specify which test tag to run."
+    echo "  -t, --tag [relay_chn|core|tilt|listener|nvs|run_limit|all]  Specify which test tag to run."
     echo ""
     echo "  If no tag is specified, it defaults to 'all'."
     echo ""