Add basic save file structure

- Create save.h with gameDataSav struct
- Add placeholder functions for save handling
- Foundation for BOTW save data manipulation

source/save_basic.c

@@ -0,0 +1,16 @@
+#include <string.h>
+#include <stdio.h>
+#include <switch.h>
+#include "save_basic.h"
+
+static gameDataSav save_data = {0};
+
+void openSave() {
+    printf("Opening BOTW save data...\n");
+    // TODO: Implement save file reading
+}
+
+void processSave() {
+    printf("Processing save data...\n");
+    // TODO: Implement save processing logic
+}