samples: subsystem: align LED and button behavior across samples

Align LED and button behavior across samples to follow a consistent
and predictable convention. The goal is to make samples easier to
understand, compare, and reuse by ensuring that common actions map
to the same LEDs and buttons wherever possible. All changes were
tested and verified on hardware, and all affected READMEs were
updated to reflect the new behavior.

Subsystem samples use LED0 to indicate initialization only.
No additional LED or button behavior is defined for these samples.

Signed-off-by: Martynas Smilingis <martynas.smilingis@nordicsemi.no>

Author: PizzaAllTheWay

samples/subsys/fs/bm_zms/README.rst

@@ -73,6 +73,12 @@ Kconfig fragments
 By default, the sample uses the SoftDevice storage backend.
 To configure it for this sample, follow the steps outlined in :ref:`sample_intro_config_build`.
 
+User interface
+**************
+
+LED 0:
+  Lit when the ZMS storage has been successfully initialized by mounting and clearing the storage.
+
 Building and running
 ********************
 

samples/subsys/fs/bm_zms/src/main.c

@@ -7,6 +7,8 @@
 #include <zephyr/kernel.h>
 #include <zephyr/logging/log.h>
 #include <zephyr/logging/log_ctrl.h>
+#include <hal/nrf_gpio.h>
+#include <board-config.h>
 
 #define STORAGE_NODE DT_NODELABEL(storage0_partition)
 #define BM_ZMS_PARTITION_OFFSET DT_REG_ADDR(STORAGE_NODE)
@@ -184,6 +186,10 @@ int main(void)
 	}
 	wait_for_clear();
 
+	nrf_gpio_cfg_output(BOARD_PIN_LED_0);
+	nrf_gpio_pin_write(BOARD_PIN_LED_0, BOARD_LED_ACTIVE_STATE);
+	LOG_INF("BM_ZMS sample initialized");
+
 	for (i = 0; i < CONFIG_SAMPLE_BM_ZMS_ITERATIONS_MAX; i++) {
 		rc = bm_zms_mount(&fs, &config);
 		if (rc) {

samples/subsys/storage/bm_storage/README.rst

@@ -73,6 +73,12 @@ Kconfig fragments
 By default, the sample uses the SoftDevice storage backend.
 To configure it for this sample, follow the steps outlined in :ref:`sample_intro_config_build`.
 
+User interface
+**************
+
+LED 0:
+  Lit when the device storage has been successfully initialized.
+
 Building and running
 ********************
 

samples/subsys/storage/bm_storage/src/main.c

@@ -14,6 +14,8 @@
 
 #include <bm/softdevice_handler/nrf_sdh.h>
 #include <nrf_soc.h>
+#include <hal/nrf_gpio.h>
+#include <board-config.h>
 
 #include <bm/storage/bm_storage.h>
 
@@ -238,6 +240,10 @@ int main(void)
 		goto idle;
 	}
 
+	nrf_gpio_cfg_output(BOARD_PIN_LED_0);
+	nrf_gpio_pin_write(BOARD_PIN_LED_0, BOARD_LED_ACTIVE_STATE);
+	LOG_INF("Storage sample initialized");
+
 	LOG_INF("Reading persisted data");
 
 	err = storage_reads();
@@ -280,7 +286,7 @@ int main(void)
 		goto idle;
 	}
 
-	LOG_INF("Storage sample finished.");
+	LOG_INF("Storage sample finished");
 
 idle:
 	/* Enter main loop. */