sample main file and fixed makefile

Makefile

@@ -52,6 +52,6 @@ clean:
 	rm -rf $(BUILDDIR)
 
 run: all
-	$(RUN_CMD) ./data/Circuit.duckdb
+	$(RUN_CMD)
 
 .PHONY: all clean run

src/main.c

@@ -0,0 +1,6 @@
+#include <stdio.h>
+
+int main() {
+    printf("Hello World!");
+    return 0;
+}