refactor: archive GUI clients; keep minimal TUI with hooks/API

Move Qt/Tauri/full Web SPA under archive/, ship hermit as CLI/TUI plus
libcstcore and cst-webui/1 HTTP+SSE (turn lifecycle hooks, capabilities).

Co-authored-by: Cursor <cursoragent@cursor.com>

CMakeLists.txt

@@ -5,8 +5,8 @@ set(CMAKE_C_STANDARD 11)
 set(CMAKE_C_STANDARD_REQUIRED ON)
 
 option(CST_BUILD_TUI "Build ncurses/PDCurses TUI" ON)
-option(CST_BUILD_WEBUI "Build the HTTP/SSE WebUI (--web)" ON)
-option(CST_BUILD_APP "Build the Qt front end in app/ (in-process engine, no port)" OFF)
+option(CST_BUILD_WEBUI "Build the HTTP/SSE engine API (--web, cst-webui/1)" ON)
+option(CST_BUILD_APP "Build archived Qt front end in archive/qt-app (experimental)" OFF)
 option(CST_NATIVE_ARCH "Pass -march=native to sashidown" OFF)
 option(CST_BUNDLE_BUSYBOX "Install placeholder/scripts for busybox beside binary" ON)
 
@@ -218,9 +218,8 @@ if(WIN32)
 endif()
 
 # --- the engine as a library ---------------------------------------------
-# cstcore is the core without main()/TUI: the CLI links it and the Qt front
-# end in app/ (CST_BUILD_APP) embeds the very same objects in-process, so the
-# engine is compiled once per build instead of once per front end.
+# cstcore is the core without main()/TUI: the CLI links it; archived clients
+# (archive/qt-app, archive/desktop-tauri) can embed the same objects in-process.
 add_library(cstcore STATIC ${CST_CORE_SOURCES})
 add_dependencies(cstcore sashidown)
 target_include_directories(cstcore PUBLIC
@@ -246,7 +245,8 @@ else()
 endif()
 
 if(CST_BUILD_APP)
-  add_subdirectory(app)
+  # Frozen reference GUI; not part of the default Hermit delivery.
+  add_subdirectory(archive/qt-app)
 endif()
 
 set(CST_SOURCES src/main.c)