feat(app): Add CAN node application

This commit introduces a new CAN node application for the irrigation system.

The application initializes the settings subsystem and the valve system. It is intended to be used on a CAN bus to control a valve.
Signed-off-by: Eduard Iten <eduard@iten.pro>

software/apps/can_node/boards/bluepill_f103rb.overlay

@@ -0,0 +1,43 @@
+/ {
+    chosen {
+        zephyr,console = &rtt;
+        zephyr,shell = &rtt;
+        zephyr,settings-partition = &storage_partition;
+    };
+
+    rtt: rtt {
+        compatible = "segger,rtt-uart";
+        #address-cells = <1>;
+        #size-cells = <0>;
+        label = "RTT";
+        status = "okay";
+    };
+};
+
+&flash0 {
+    partitions {
+        compatible = "fixed-partitions";
+        #address-cells = <1>;
+        #size-cells = <1>;
+
+        /* Application partition starts at the beginning of flash */
+        slot0_partition: partition@0 {
+            label = "image-0";
+            reg = <0x00000000 DT_SIZE_K(120)>;
+        };
+
+        /* Use the last 8K for settings */
+        storage_partition: partition@1E000 {
+            label = "storage";
+            reg = <0x0001E000 DT_SIZE_K(8)>;
+        };
+    };
+};
+
+&usart1 {
+	modbus0 {
+		compatible = "zephyr,modbus-serial";
+		status = "okay";
+	};
+	status = "okay";
+};