Settings: Install updates, when asked or by itself

Off by default: what runs on the device changes only when its owner
said it may (issue #52).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0162FokPdvY2KsS4NBfwyWPk

lib/services/src/settings.h

@@ -44,6 +44,7 @@ enum class Setting : uint8_t {
     LauncherList,     // bool: the Launcher is a list of names instead of a grid of icons (issue #9)
     Theme,            // int: the colour theme, an index into ui::palette (issue #10)
     ThemeLight,       // bool: its light side instead of its dark one
+    InstallUpdates,   // bool: a newer release found by the daily check is installed without being asked for (issue #52)
     Count
 };