Add KiCad WASM build infrastructure and dependency scripts

- Add build environment setup (scripts/common/env.sh, versions.sh, functions.sh)
- Add dependency build scripts for Zstd, GLM, FreeType, HarfBuzz, Pixman, Cairo
- Add placeholder scripts for OpenCASCADE, ngspice, protobuf
- Add WASM compatibility layer (wasm/kiplatform/, wasm/libcontext/)
- Add CMake modules for KiCad WASM cross-compilation
- Add PCBnew test infrastructure (tests/kicad/)
- Add build plan documentation

Successfully tested builds: Zstd 1.5.5, GLM 0.9.9.8, FreeType 2.13.2,
HarfBuzz 8.3.0, Pixman 0.42.2, Cairo 1.18.0

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

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

scripts/common/versions.sh

@@ -0,0 +1,51 @@
+#!/bin/bash
+# Dependency versions for KiCad WASM build
+# These versions match KiCad 8.99 requirements from CMakeLists.txt and vcpkg.json
+
+# KiCad submodule version
+export KICAD_COMMIT="4bfed3f1746e8cc0a7d942767770f56fa28b393c"
+export KICAD_VERSION="8.99"
+
+# From vcpkg.json overrides (pinned versions)
+export GLM_VERSION="0.9.9.8"
+export NGSPICE_VERSION="45.2"
+export PROTOBUF_VERSION="3.21.12"
+export PYTHON_VERSION="3.11.5"
+export WXWIDGETS_VERSION="3.3.1"
+
+# From CMakeLists.txt minimum requirements
+export WXWIDGETS_MIN="3.2.0"
+export GLM_MIN="0.9.8"
+export BOOST_MIN="1.71.0"
+export FREETYPE_MIN="2.11.1"
+export CAIRO_MIN="1.12"
+export PIXMAN_MIN="0.30"
+export LIBGIT2_MIN="1.5"
+export OCC_MIN="7.5.0"
+export SWIG_MIN="4.0"
+
+# Recommended versions for WASM build
+export OCC_VERSION="7.8.0"
+export ZSTD_VERSION="1.5.5"
+export FREETYPE_VERSION="2.13.2"
+export HARFBUZZ_VERSION="8.3.0"
+export CAIRO_VERSION="1.18.0"
+export PIXMAN_VERSION="0.42.2"
+export BOOST_VERSION="1.84.0"
+
+# Download URLs
+export ZSTD_URL="https://github.com/facebook/zstd/releases/download/v${ZSTD_VERSION}/zstd-${ZSTD_VERSION}.tar.gz"
+export FREETYPE_URL="https://download.savannah.gnu.org/releases/freetype/freetype-${FREETYPE_VERSION}.tar.xz"
+export HARFBUZZ_URL="https://github.com/harfbuzz/harfbuzz/releases/download/${HARFBUZZ_VERSION}/harfbuzz-${HARFBUZZ_VERSION}.tar.xz"
+export CAIRO_URL="https://cairographics.org/releases/cairo-${CAIRO_VERSION}.tar.xz"
+export PIXMAN_URL="https://cairographics.org/releases/pixman-${PIXMAN_VERSION}.tar.gz"
+export OCC_URL="https://github.com/Open-Cascade-SAS/OCCT/archive/refs/tags/V${OCC_VERSION//./_}.tar.gz"
+export NGSPICE_URL="https://sourceforge.net/projects/ngspice/files/ng-spice-rework/${NGSPICE_VERSION}/ngspice-${NGSPICE_VERSION}.tar.gz/download"
+
+# SHA256 checksums (to be filled in after first successful download)
+# export ZSTD_SHA256=""
+# export HARFBUZZ_SHA256=""
+# export CAIRO_SHA256=""
+# export PIXMAN_SHA256=""
+# export OCC_SHA256=""
+# export NGSPICE_SHA256=""