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.cpp

@@ -56,6 +56,7 @@ const Definition kDefinitions[] = {
     {"launcher_list", Kind::Bool, 0, nullptr, 0, 1},  // off: the grid
     {"theme", Kind::Int, 0, nullptr, 0, 6},  // roro9stack's own; ui::kThemeCount of them
     {"theme_light", Kind::Bool, 0, nullptr, 0, 1},
+    {"auto_install", Kind::Bool, 0, nullptr, 0, 1},  // off: what runs here changes only when someone says so
 };
 static_assert(sizeof(kDefinitions) / sizeof(kDefinitions[0]) == static_cast<size_t>(Setting::Count),
               "every Setting needs a definition");