[refactor] Organize STRING

kernel/graphics/layer.cpp

@@ -7,7 +7,7 @@
 #include <serial.h>
 #include <idt.h>
 #include <pic.h>
-#include <common.h>
+#include <string_utils.h>
 
 // --- Layer list (sorted by z, lowest first) ---
 
@@ -84,12 +84,7 @@ layer_t* layer_create(const char* name, layer_type_t type, UINT32 w, UINT32 h) {
     layer->visible = true;
     layer->next = NULL;
 
-    const char* s = name;
-    char* d = layer->name;
-    for (SSINT32 i = 0; i < LAYER_NAME_LEN - 1 && *s; i++) {
-        *d++ = *s++;
-    }
-    *d = '\0';
+    str_copy(layer->name, name, LAYER_NAME_LEN);
 
     UINTN buf_size = (UINTN)w * h * sizeof(EFI_GRAPHICS_OUTPUT_BLT_PIXEL);
     layer->buffer = (EFI_GRAPHICS_OUTPUT_BLT_PIXEL*)kmalloc(buf_size);