Add reproducible build system for wxWidgets WASM port

- Add unified patch (wxwidgets-wasm.patch) for build validation
- Add scripts:
  - generate-wxwidgets-patches.sh: Extract patches from wxwidgets state
  - build-wxwidgets-wasm-clean.sh: Build from clean clone + patches
  - build-wxuniversal-wasm.sh: Build wxWidgets for WASM
- Add wxWidgets-wasm-reference submodule (ahilss/wxWidgets-wasm)
- Update .gitignore for wxwidgets-clean/ directory

Base commit: 5ff25322553c1870cf20a2e1ba6f20ed50d9fe9a

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

scripts/build-wxuniversal-wasm.sh

@@ -0,0 +1,72 @@
+#!/bin/bash
+# Build wxWidgets with wxUniversal for WebAssembly
+# This builds the GUI-enabled wxWidgets needed for KiCad
+
+set -e
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+PROJECT_ROOT="$(dirname "$SCRIPT_DIR")"
+BUILD_DIR="$PROJECT_ROOT/build-wasm/wxwidgets-universal"
+WX_SOURCE="$PROJECT_ROOT/wxwidgets"
+
+echo "=== Building wxWidgets wxUniversal for WASM ==="
+echo "Project root: $PROJECT_ROOT"
+echo "Build dir: $BUILD_DIR"
+echo "wxWidgets source: $WX_SOURCE"
+
+# Verify we're in the right place
+if [ ! -f "$WX_SOURCE/configure" ]; then
+    echo "ERROR: wxWidgets source not found at $WX_SOURCE"
+    echo "Make sure the wxwidgets submodule is initialized"
+    exit 1
+fi
+
+# Clean if requested
+if [ "$1" = "--clean" ]; then
+    echo "Cleaning build directory..."
+    rm -rf "$BUILD_DIR"
+fi
+
+# Create build directory
+mkdir -p "$BUILD_DIR"
+cd "$BUILD_DIR"
+
+# Configure with emconfigure
+# Key flags based on wxWidgets-wasm:
+# --host=emscripten          Host system (detected via config.sub)
+# --enable-universal         Use wxUniversal (draws widgets directly)
+# --disable-shared           Build static libraries
+# --with-opengl              Enable OpenGL/WebGL support
+# --disable-exceptions       Emscripten doesn't support C++ exceptions well
+# --disable-richtext         Not needed for KiCad, simplifies build
+# --without-libtiff          Avoid external dependencies
+# --disable-xlocale          Browser environment handles locale
+
+echo ""
+echo "=== Configuring ==="
+
+# Set flags for Emscripten compatibility
+# Z_HAVE_UNISTD_H ensures zlib includes <unistd.h> for read/write/lseek
+export CFLAGS="-DZ_HAVE_UNISTD_H=1"
+export CXXFLAGS="-DZ_HAVE_UNISTD_H=1"
+
+emconfigure "$WX_SOURCE/configure" \
+    --host=emscripten \
+    --enable-universal \
+    --disable-shared \
+    --with-opengl \
+    --disable-exceptions \
+    --disable-richtext \
+    --without-libtiff \
+    --disable-xlocale \
+    --with-cxx=17 \
+    --enable-utf8
+
+# Build
+echo ""
+echo "=== Building ==="
+emmake make -j$(nproc 2>/dev/null || sysctl -n hw.ncpu)
+
+echo ""
+echo "=== Build complete ==="
+ls -lh "$BUILD_DIR"/lib/*.a 2>/dev/null || echo "Libraries built in $BUILD_DIR/lib"