refactor(structure): normalize folder names with leading zeros for consistency

- Renamed all folders from format NEx (e.g., 1Ex, 2Ex...) to 0NEx (01Ex, 02Ex, etc.)
- Updated subdirectories and files accordingly
- Removed old main Makefile and tasks (a01.c–a09.c, solve.c, io_status.h), likely obsolete
- Cleaned up deprecated task binaries and configs

2025.02.28/03Ex/sort.c

@@ -0,0 +1,23 @@
+#include "sort.h"
+
+int up_strcmp(const char *a, const char *b)
+{ return strcmp(a, b); }
+
+int down_strcmp(const char *a, const char *b)
+{ return -strcmp(a, b); }
+
+int up_len(const char *a, const char *b)
+{
+	int i = 0;
+	while (1)
+	{
+		if (a[i] == '\0' && b[i] == '\0') return strcmp(a, b);
+		else if (a[i] == '\0') return -1;
+		else if (b[i] == '\0') return 1;
+
+		i++;
+	}
+}
+int down_len(const char *a, const char *b)
+{ return -up_len(a, b); }
+