fix: avoid dangling pointers to local storage

helpers/flipchess_file.c

@@ -16,10 +16,10 @@
 bool flipchess_has_file(const FlipChessFile file_type, const char* file_name, const bool remove) {
     bool ret = false;
     const char* path;
+    char path_buf[FILE_MAX_PATH_LEN] = {0};
     if(file_type == FlipChessFileBoard) {
         path = FLIPCHESS_BOARD_PATH;
     } else {
-        char path_buf[FILE_MAX_PATH_LEN] = {0};
         strcpy(path_buf, FLIPCHESS_APP_BASE_FOLDER); // 22
         strcpy(path_buf + strlen(path_buf), "/");
         strcpy(path_buf + strlen(path_buf), file_name);