sys: Implement LAPIC and IOAPIC support, add PS/2 keyboard driver

- Added LAPIC implementation in `apic.c` and `apic.h`, including initialization and basic operations.
- Introduced IOAPIC (I/O Advanced Programmable Interrupt Controller) support in `ioapic.c` and `ioapic.h`, parsing the ACPI MADT to locate IOAPICs and manage redirection entries.
- Implemented PS/2 keyboard driver in `ps2.c` and `ps2.h`, handling keyboard interrupts and translating scancodes to ASCII.
- Attempted to make usermode work again (it failed, coming soon)
- Cleaned up comments in `time.c` and `render.c` for clarity.

Signed-off-by: kaguya <vpshinomiya@protonmail.com>

user/crt0.S

@@ -1,12 +1,12 @@
-.global _start
-
 .section .text
+.global _start
 _start:
-    call main
-
-    mov $60, %rax   # exit syscall (you define this later)
-    xor %rdi, %rdi
+    mov $1, %rax
+    mov $'H', %rdi
     syscall
 
-hang:
-    jmp hang
+    mov $1, %rax
+    mov $'i', %rdi
+    syscall
+
+1:  jmp 1b