feat: system settings stored as applets in virtual folder

programs/src/desktop/apps/apps_common.hpp

@@ -155,6 +155,41 @@ inline void format_size(char* buf, int size) {
     }
 }
 
+// ============================================================================
+// Desktop builtins
+// ============================================================================
+
+enum DesktopBuiltinId : int {
+    DESKTOP_BUILTIN_NONE = -1,
+    DESKTOP_BUILTIN_FILES = 1,
+    DESKTOP_BUILTIN_DESKTOP_SETTINGS = 11,
+    DESKTOP_BUILTIN_REBOOT = 12,
+    DESKTOP_BUILTIN_SHUTDOWN = 14,
+    DESKTOP_BUILTIN_LOG_OUT = 16,
+    DESKTOP_BUILTIN_LOCK_SCREEN = 17,
+    DESKTOP_BUILTIN_SLEEP = 18,
+    DESKTOP_BUILTIN_USER_MANAGEMENT = 19,
+    DESKTOP_BUILTIN_SYSTEM_CONFIGURATION = 20,
+};
+
+inline constexpr const char* FILEMANAGER_PATH_SYSTEM_CONFIGURATION =
+    "virtual://system-configuration";
+
+struct DesktopBuiltinEntry {
+    DesktopBuiltinId id;
+    const char* label;
+    int launcher_category;
+    bool launcher_footer;
+    bool system_tools_applet;
+    const char* icon_path;
+};
+
+const DesktopBuiltinEntry* desktop_builtin_registry(int* count);
+const DesktopBuiltinEntry* desktop_builtin_entry(DesktopBuiltinId id);
+SvgIcon* desktop_builtin_menu_icon(DesktopState* ds, DesktopBuiltinId id);
+void desktop_launch_builtin(DesktopState* ds, DesktopBuiltinId id);
+void desktop_lock_screen(DesktopState* ds);
+
 // ============================================================================
 // Forward declarations for desktop launch entry points
 // ============================================================================
@@ -167,6 +202,7 @@ void open_calculator(DesktopState* ds);
 void open_texteditor(DesktopState* ds);
 void open_klog(DesktopState* ds);
 void open_settings(DesktopState* ds);
+void open_user_manager(DesktopState* ds);
 void open_reboot_dialog(DesktopState* ds);
 void open_wordprocessor(DesktopState* ds);
 void open_shutdown_dialog(DesktopState* ds);