feat: add build numbering

programs/include/Api/Syscall.hpp

@@ -243,6 +243,7 @@ namespace Montauk {
         char osVersion[32];
         uint32_t    apiVersion;
         uint32_t    maxProcesses;
+        uint32_t    buildNumber;   // monotonic kernel build number
     };
 
     struct KeyEvent {

programs/src/desktop/apps/settings/about.cpp

@@ -23,14 +23,15 @@ void settings_draw_about(Canvas& c, SettingsState* st) {
         ? fonts::system_font->get_line_height(fonts::LARGE_SIZE) : (FONT_HEIGHT * 2);
     y += large_h + 8;
 
-    snprintf(line, sizeof(line), "Version %s", st->sys_info.osVersion);
+    snprintf(line, sizeof(line), "Version %s (Build %u)",
+             st->sys_info.osVersion, (unsigned)st->sys_info.buildNumber);
     c.text(x, y, line, theme.text);
     y += line_h + 8;
 
     mtk::draw_separator(c, x, y, c.w - 2 * x, theme);
     y += 12;
 
-    snprintf(line, sizeof(line), "API version: %d", (int)st->sys_info.apiVersion);
+    snprintf(line, sizeof(line), "Build number: %u", (unsigned)st->sys_info.buildNumber);
     c.kv_line(x, &y, line, theme.text, line_h);
 
     int up_sec = (int)(st->uptime_ms / 1000);