feat(project): Restructure software for multi-app setup

- Reorganize the software directory to support multiple Zephyr applications (gateway, slave_node).

- Create a clear separation between applications and shared libraries.

- Add placeholder files for gateway and slave_node applications.

software/apps/gateway/CMakeLists.txt

@@ -0,0 +1,6 @@
+cmake_minimum_required(VERSION 3.20)
+
+find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
+project(gateway)
+
+target_sources(app PRIVATE src/main.c)

software/apps/gateway/prj.conf

@@ -0,0 +1,3 @@
+# Zephyr configuration for the Gateway
+CONFIG_NETWORKING=y
+CONFIG_NET_TCP=y

software/apps/gateway/src/main.c

@@ -0,0 +1,13 @@
+/*
+ * Copyright (c) 2025 Eduard Iten
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr/kernel.h>
+
+int main(void)
+{
+	printk("Hello from Gateway!\n");
+	return 0;
+}