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>

src/syscall/syscall.c

@@ -57,7 +57,7 @@ void syscall_init(void)
     extern void syscall_entry(void);
 
     uint64_t kernel_cs = 0x08;
-    uint64_t user_cs   = 0x1B;
+    uint64_t user_cs   = 0x23;
 
     uint64_t star =
         ((uint64_t)kernel_cs << 32) |