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'

kernel/cpp/cxx_runtime.cpp

@@ -16,7 +16,7 @@ extern "C" {
     extern ctor_fn_t __init_array_end[];
 
     void cpp_call_global_constructors(void) {
-        if (__init_array_end <= __init_array_start) return;
+        if (+__init_array_end <= +__init_array_start) return;
         size_t count = __init_array_end - __init_array_start;
         for (size_t i = 0; i < count; i++) {
             if (__init_array_start[i]) {