* tutorial(cpp-ui): rewrite Part 3 to the universal authoring model
calc_ui_cpp now uses interface: universal — you write only the .rep and a
CalcUiCppBackend deriving CalcUiCppSimpleSource + LogosModuleContext, calling
modules().calc_module.* (typed SDK). The *Plugin/*Interface classes,
initLogos, and setBackend wiring are generated; the hand-written interface +
plugin steps are gone. CMake uses REP_FILE + the backend sources + INCLUDE_DIRS.
Regenerated outputs/tutorial-cpp-ui-app.md and outputs/logos-calc-ui-cpp/.
Verified end to end: the full Part 1->2->3 chain runs 69/69 against the
universal templates (logos-module-builder feat/universal-templates), including
the live UI drive (Add -> 8) and the integration-test build.
Depends on the logos-module-builder universal-templates change so that the
#ui-qml-backend scaffold is the universal form.
* tutorial(cpp-ui): derive module NAME from metadata.json in CMake
Match the templates: read the name via file(READ metadata.json) +
string(JSON ... name) and pass NAME ${MODULE_NAME} to logos_module(), so the
module name has a single source of truth. Same string(JSON) pattern the
converted templates use (build-verified there).
Dario Lipicar