feat: add IMGUI_USE_WCHAR32 support, cross-compile natives, publish to mvn.mrlokop.dev

- Enable IMGUI_USE_WCHAR32 in imconfig.h (ImWchar = uint32_t)
- Extend ImFontGlyphRangesBuilder, ImFontConfig, ImFontAtlas for 32-bit codepoints
- Cross-compile natives for macOS universal, Linux x86_64 (glibc), Windows x86_64
- Publish as org.nnstd.imgui:...:1.90.0-wchar32+mrlokop2 to mvn.mrlokop.dev
- Add BUILDING.md with full rebuild and publish instructions

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

buildSrc/scripts/vendor_freetype.sh

@@ -35,16 +35,23 @@ echo "FreeType unzipped to $LIBDIR"
 COMMON_FLAGS="--enable-static --disable-shared --without-zlib --without-bzip2 --without-png --without-harfbuzz --without-brotli"
 
 # Function to configure and build FreeType
+# Args: cflags prefix output_dir [cc]
 build_freetype() {
     cflags=$1
     prefix=$2
     output_dir=$3
+    cc=${4:-}
 
     echo "Cleaning previous builds..."
     make clean
 
-    echo "Configuring FreeType with CFLAGS='$cflags' and PREFIX='$prefix'..."
-    ./configure CFLAGS="$cflags" $COMMON_FLAGS $prefix
+    if [ -n "$cc" ]; then
+        echo "Configuring FreeType with CC='$cc' CFLAGS='$cflags' and PREFIX='$prefix'..."
+        ./configure CC="$cc" CFLAGS="$cflags" $COMMON_FLAGS $prefix
+    else
+        echo "Configuring FreeType with CFLAGS='$cflags' and PREFIX='$prefix'..."
+        ./configure CFLAGS="$cflags" $COMMON_FLAGS $prefix
+    fi
     if [ $? -ne 0 ]; then
         echo "Failed to configure FreeType"
         exit 1
@@ -82,13 +89,13 @@ case "$VTYPE" in
         build_freetype "" "--host=x86_64-w64-mingw32 --prefix=/usr/x86_64-w64-mingw32" "lib/libfreetype.a"
         ;;
     linux)
-        build_freetype "-fPIC" "" "lib/libfreetype.a"
+        build_freetype "-fPIC" "--host=x86_64-unknown-linux-gnu" "lib/libfreetype.a" "x86_64-unknown-linux-gnu-gcc"
         ;;
     macos)
         MACOS_VERSION=10.15
 
-        build_freetype "-arch x86_64 -mmacosx-version-min=$MACOS_VERSION" "" "tmp/libfreetype-x86_64.a"
-        build_freetype "-arch arm64 -mmacosx-version-min=$MACOS_VERSION" "" "tmp/libfreetype-arm64.a"
+        build_freetype "-arch x86_64 -mmacosx-version-min=$MACOS_VERSION" "--host=x86_64-apple-darwin" "tmp/libfreetype-x86_64.a"
+        build_freetype "-arch arm64 -mmacosx-version-min=$MACOS_VERSION" "--host=aarch64-apple-darwin" "tmp/libfreetype-arm64.a"
 
         echo "Creating universal library using lipo..."
         lipo -create -output lib/libfreetype.a tmp/libfreetype-x86_64.a tmp/libfreetype-arm64.a