feat: Smooth Snake game rendering and expand kernel subsystems

- Implement flicker-free atomic double-buffered frame rendering and sub-tick input polling in userland/lazybox/snake.c
- Add multi-input support (PS/2 keyboard scancodes and serial ANSI arrow escape sequences)
- Add sound effects (food beep, game over chime) and live speed scaling (+/- keys, P to pause)
- Add POSIX /dev/shm shared memory subsystem in ipc/shm_posix.c and include/ipc/shm_posix.h
- Add DNS resolver cache with TTL tracking in net/ipv4/dns_cache.c and include/net/dns_cache.h
- Add audio tone and jingle synthesizer in sound/beep.c and include/sound/beep.h
- Add %o octal formatting support in lib/vsprintf.c
- Add LazyBox applets: 'shm', 'dnscache', and 'beep'

lib/vsprintf.c

@@ -145,6 +145,11 @@ int vsnprintf(char* buf, size_t size, const char* fmt, va_list args) {
                 out_idx += format_number(buf + out_idx, size - out_idx, val, 10, false, false, width, pad, left_align);
                 break;
             }
+            case 'o': {
+                uint64_t val = is_long_long ? va_arg(args, uint64_t) : (is_long ? va_arg(args, unsigned long) : va_arg(args, unsigned int));
+                out_idx += format_number(buf + out_idx, size - out_idx, val, 8, false, false, width, pad, left_align);
+                break;
+            }
             case 'x': {
                 uint64_t val = is_long_long ? va_arg(args, uint64_t) : (is_long ? va_arg(args, unsigned long) : va_arg(args, unsigned int));
                 out_idx += format_number(buf + out_idx, size - out_idx, val, 16, false, false, width, pad, left_align);