Build the live C++ preview

The gallery source retains its MIT licence. The combined WebAssembly preview
uses Qt's GPLv3 platform plugin and is distributed under GPLv3.

Install CMake, Ninja, a host Qt 6.11.2 development installation and
Emscripten 4.0.7. No account or private source is required.
Emscripten installation: https://emscripten.org/docs/getting_started/downloads.html

1. Activate Emscripten:
   ./emsdk install 4.0.7
   ./emsdk activate 4.0.7
   source ./emsdk_env.sh

2. Extract qtbase-everywhere-src-6.11.2.tar.xz. Its .tag is
   ef55f427f2c8b410d34f8a7681020a3000cf6866, matching the distributed SDK.
   Configure and build it in a separate directory:

   mkdir qt-build
   cd qt-build
   ../qtbase-everywhere-src-6.11.2/configure \
     -qt-host-path /path/to/host-qt-6.11.2 \
     -platform wasm-emscripten -prefix /path/to/qt-wasm \
     -release -static -no-feature-thread -nomake examples -nomake tests
   cmake --build . --parallel 3
   cmake --install .

   The official SDK configuration is also supplied as config_qtbase.opt
   and config_qtbase.summary. The source revision matches; binary byte
   reproducibility across host compilers is not claimed.

3. Extract gallery-source.tar.xz into a new directory. From that directory:

   cmake -S . -B build -G Ninja \
     -DCMAKE_TOOLCHAIN_FILE=/path/to/qt-wasm/lib/cmake/Qt6/qt.toolchain.cmake \
     -DQT_HOST_PATH=/path/to/host-qt-6.11.2 \
     -DCMAKE_BUILD_TYPE=Release -DCMAKE_CXX_STANDARD=23 \
     -DSHADCN_BUILD_TESTS=OFF -DSHADCN_BUILD_EXAMPLES=ON
   cmake --build build --parallel 3

4. Serve the generated shadcn_gallery.html, shadcn_gallery.js,
   shadcn_gallery.wasm and qtloader.js with a static web server.
   The documentation's HTML host is available at ../index.html.
   It selects the component and theme through command line arguments.
   The WebAssembly build uses the same component and gallery C++ sources.

The SDK build used Emscripten 4.0.7. Runtime source is available at:
https://github.com/emscripten-core/emscripten/tree/8dc91db45bf96c174531006839472a3924d105aa
Runtime licences are supplied in ../licenses/.