Add firmware_node app - Step 1: Shell with reset command

- Create new Zephyr app for firmware management
- Target: weact_stm32g431_core board
- Features: Shell interface with custom reset command
- Tested on Zephyr 4.1.99
- Flash usage: 55,400 bytes (42.27% of 128KB)
- RAM usage: 12,864 bytes (39.26% of 32KB)
- Black Magic Probe flash runner support

software/apps/firmware_node/src/main.c

@@ -0,0 +1,28 @@
+#include <zephyr/kernel.h>
+#include <zephyr/shell/shell.h>
+#include <zephyr/sys/reboot.h>
+#include <zephyr/logging/log.h>
+
+LOG_MODULE_REGISTER(firmware_node, LOG_LEVEL_DBG);
+
+static int cmd_reset(const struct shell *shell, size_t argc, char **argv)
+{
+    ARG_UNUSED(argc);
+    ARG_UNUSED(argv);
+    
+    shell_print(shell, "Rebooting system...");
+    k_msleep(100); // Give time for message to be sent
+    sys_reboot(SYS_REBOOT_WARM);
+    
+    return 0;
+}
+
+SHELL_CMD_REGISTER(reset, NULL, "Reset the system", cmd_reset);
+
+int main(void)
+{
+    LOG_INF("Firmware Node starting up");
+    LOG_INF("Shell with reset command available");
+    
+    return 0;
+}