feat ✨: Add GitHub Actions workflow for SDCC build and test on CC2530

- This commit adds a new GitHub Actions workflow for building and testing SDCC (Software Development Compiler) on CC2530.
- The changes are to update the build process for Zigbee sensor firmware, switching from MSP430 compiler to sdcc and updating object file generation rules.
- This commit updates the build system for the project, adding and configuring new paths, compiler settings, and dependencies for the Z-Stack SDK.

Makefile.old

@@ -0,0 +1,33 @@
+# Path to Z-Stack SDK
+ZSTACK_DIR = ./include
+
+# Include path for the Z-Stack SDK
+# INCLUDE_DIRS = -I$(ZSTACK_DIR)/Components/hal/CC2530 \
+#                -I$(ZSTACK_DIR)/Components/zigbee
+INCLUDE_DIRS = -I$(ZSTACK_DIR)
+
+# Compiler settings
+CC = msp430-elf-gcc	# MSP430 compiler
+# CFLAGS (C Compiler flags)
+CFLAGS = $(INCLUDE_DIRS) -Wall -O2	# Enable all warnings, Optimize for size
+LDFLAGS =
+LIBS = -lZStack -lhal	# ZStack for Zigbee communication, lhal for Hardware Abstraction Layer library
+
+SRCS = main.c zigbee_comm.c sensors/bme280.c sensors/wind_vane.c sensors/rain_gauge.c sensors/anemometer.c include/hal_timer.c 
+HEADERS = main.h zigbee_comm.h sensors/bme280.h sensors/wind_vane.h sensors/rain_gauge.h sensors/anemometer.h config.h include/hal_types.h include/hal_defs.h include/hal_timer.h include/ZComDef.h include/OSAL.h include/i2c.h
+OBJS = $(SRCS:.c=.o)	# create a list of object files from the source files
+
+all: main.elf
+
+main.elf: $(OBJS)
+	$(CC) $(LDFLAGS) $(OBJS) $(LIBS) -o $@
+
+%.o: %.c $(HEADERS)
+	$(CC) $(CFLAGS) -c $< -o $@
+
+clean:
+	rm -f main.elf $(OBJS)
+
+# Optionally add a rule to flash your device (if applicable)
+# flash: main.elf
+#	./flash_tool main.elf  # This is just a placeholder if needed