feat: add time offset configuration

programs/include/Api/Syscall.hpp

@@ -116,6 +116,10 @@ namespace Montauk {
     // Power management
     static constexpr uint64_t SYS_SUSPEND      = 89;
 
+    // Timezone
+    static constexpr uint64_t SYS_SETTZ         = 90;
+    static constexpr uint64_t SYS_GETTZ         = 91;
+
     // Audio control commands (for SYS_AUDIOCTL)
     static constexpr int AUDIO_CTL_SET_VOLUME = 0;
     static constexpr int AUDIO_CTL_GET_VOLUME = 1;

programs/include/gui/desktop.hpp

@@ -52,6 +52,7 @@ struct DesktopSettings {
     bool show_shadows;      // window shadows on/off
     bool clock_24h;         // 24-hour clock format
     int ui_scale;           // 0=Small, 1=Default, 2=Large
+    int tz_offset_minutes;  // timezone offset from UTC in minutes
 };
 
 struct DesktopState {

programs/include/libc/montauk.h

@@ -94,6 +94,8 @@ extern "C" {
 #define MTK_SYS_AUDIOCLOSE      81
 #define MTK_SYS_AUDIOWRITE      82
 #define MTK_SYS_AUDIOCTL        83
+#define MTK_SYS_SETTZ           90
+#define MTK_SYS_GETTZ           91
 
 #define MTK_SOCK_TCP 1
 #define MTK_SOCK_UDP 2
@@ -411,6 +413,14 @@ static inline void mtk_gettime(mtk_datetime *out) {
     _mtk_syscall1(MTK_SYS_GETTIME, (long)out);
 }
 
+static inline void mtk_settz(int offset_minutes) {
+    _mtk_syscall1(MTK_SYS_SETTZ, (long)offset_minutes);
+}
+
+static inline int mtk_gettz(void) {
+    return (int)_mtk_syscall0(MTK_SYS_GETTZ);
+}
+
 /* ====================================================================
    System info
    ==================================================================== */

programs/include/montauk/syscall.h

@@ -249,6 +249,10 @@ namespace montauk {
     // Timekeeping (wall-clock)
     inline void gettime(Montauk::DateTime* out) { syscall1(Montauk::SYS_GETTIME, (uint64_t)out); }
 
+    // Timezone offset (total minutes from UTC)
+    inline void settz(int offset_minutes) { syscall1(Montauk::SYS_SETTZ, (uint64_t)(int64_t)offset_minutes); }
+    inline int gettz() { return (int)syscall0(Montauk::SYS_GETTZ); }
+
     // Random number generation
     inline int64_t getrandom(void* buf, uint32_t len) {
         return syscall2(Montauk::SYS_GETRANDOM, (uint64_t)buf, (uint64_t)len);