Multiple changes:

- Makefile: fix linker script path
- irq.c: `irqN()` stubs
- irq.h: fix missing header
- isr.h/isr.c extern `interrupt_handlers`
- utils.c: remove duplicate `memcmp`

kernel/utils.h

@@ -9,7 +9,6 @@ char* itoa(int value, char* str, int base);
 // Convert unsigned integer to string (base is typically 10, 16, etc.)
 char* utoa(unsigned int value, char* str, int base);
 
-int memcmp(const void *ptr1, const void *ptr2, size_t num);
 void *memset(void *dest, int value, size_t len);
 
 #endif // UTILS_H