feat: Establish functional multi-app structure

This commit captures a working multi-app build where the board definition is located in the 'software' directory and explicitly included by the slave_node application. This serves as a stable baseline.

software/apps/gateway/prj.conf

@@ -1,3 +1,2 @@
-# Zephyr configuration for the Gateway
+# Gateway Configuration
 CONFIG_NETWORKING=y
-CONFIG_NET_TCP=y

software/apps/slave_node/CMakeLists.txt

@@ -1,6 +1,11 @@
 cmake_minimum_required(VERSION 3.20)
 
+# Point BOARD_ROOT and DTS_ROOT to the main 'software' directory
+# so Zephyr can find the 'boards' subdirectory there.
+list(APPEND BOARD_ROOT ${CMAKE_CURRENT_SOURCE_DIR}/../..)
+list(APPEND DTS_ROOT ${CMAKE_CURRENT_SOURCE_DIR}/../..)
+
 find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
 project(slave_node)
 
-target_sources(app PRIVATE src/main.c)
+target_sources(app PRIVATE src/main.c)

software/apps/slave_node/prj.conf

@@ -1,2 +1,7 @@
-# Zephyr configuration for the Slave Node
+# --- Base Slave Node Config ---
 CONFIG_GPIO=y
+
+# Use RTT for console output instead of UART
+CONFIG_USE_SEGGER_RTT=y
+CONFIG_RTT_CONSOLE=y
+CONFIG_UART_CONSOLE=n

software/apps/slave_node/src/main.c

@@ -8,6 +8,9 @@
 
 int main(void)
 {
-	printk("Hello from Slave Node!\n");
+	while (1) {
+		printk("Hello from Slave Node!\n");
+		k_msleep(1000);
+	}
 	return 0;
 }