feat: restructure

library.c

@@ -1,4 +1,4 @@
-#include "include/library.h"
+#include "tstd/library.h"
 
 #include <stdio.h>
 

string.c

@@ -1,7 +1,4 @@
-#include  "include/string.h"
-#include <stdlib.h>
-#include <string.h>
-
+#include  "tstd/string.h"
 
 size_t str_count_occurrences(const char* str, const char c) {
     size_t i = 0;

test/test_main.c

@@ -2,7 +2,7 @@
 // Created by tilok on 23.08.2025.
 //
 
-#include "string.h"
+#include "tstd/string.h"
 #include <assert.h>
 #include <stdio.h>