Add KiCad PCBnew build script and CMake Find modules

- Add scripts/kicad/build-pcbnew.sh with clean-by-default and --no-clean flag
- Remove old scripts/build-pcbnew-wasm.sh (moved to scripts/kicad/)
- Add Boost build script with Emscripten toolset for Boost.Locale
- Add header download scripts for CURL and libgit2 (stub libraries)
- Add CMake Find modules for cross-compilation compatibility:
  - FindGLM.cmake: Reads version from setup.hpp
  - FindZSTD.cmake: Explicit sysroot paths
  - FindCURL.cmake: Header-only stub
  - FindSPNAV.cmake: Disabled (3D mouse not needed in browser)
  - FindCairo.cmake: Finds our built Cairo
  - FindPixman.cmake: Finds our built Pixman
  - Findlibgit2.cmake: Header-only stub
- Fix OpenCASCADE build: correct extracted dir name, add CMake policy
- Fix Protobuf build: correct GitHub release tag format (v21.12 not v3.21.12)

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

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

scripts/kicad/build-pcbnew.sh

@@ -0,0 +1,127 @@
+#!/bin/bash
+# Build KiCad PCBnew for WebAssembly
+# This builds the PCB editor as a standalone WASM application
+#
+# Usage:
+#   ./scripts/kicad/build-pcbnew.sh [options]
+#
+# Options:
+#   --no-clean    Skip cleaning the build directory (default: clean before build)
+#   --skip-deps   Skip building dependencies
+#   --debug       Build with debug symbols
+
+set -e
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+source "${SCRIPT_DIR}/../common/env.sh"
+source "${SCRIPT_DIR}/../common/versions.sh"
+source "${SCRIPT_DIR}/../common/functions.sh"
+
+KICAD_DIR="${PROJECT_ROOT}/kicad"
+KICAD_BUILD="${BUILD_ROOT}/kicad-pcbnew"
+KICAD_STAMP="${BUILD_ROOT}/stamps/kicad-pcbnew.stamp"
+WASM_LAYER="${PROJECT_ROOT}/wasm"
+WX_BUILD="${BUILD_ROOT}/wxwidgets-universal"
+
+# Parse arguments - clean by default
+NO_CLEAN=0
+SKIP_DEPS=0
+DEBUG=0
+for arg in "$@"; do
+    case $arg in
+        --no-clean)
+            NO_CLEAN=1
+            ;;
+        --skip-deps)
+            SKIP_DEPS=1
+            ;;
+        --debug)
+            DEBUG=1
+            ;;
+    esac
+done
+
+# Step 1: Clean build directory (default behavior)
+if [ $NO_CLEAN -eq 0 ]; then
+    log_info "Cleaning KiCad PCBnew build directory..."
+    rm -rf "${KICAD_BUILD}" "${KICAD_STAMP}"
+else
+    log_info "Skipping clean (--no-clean specified)"
+fi
+
+# Step 2: Build dependencies
+if [ $SKIP_DEPS -eq 0 ]; then
+    log_info "Building dependencies..."
+    "${SCRIPT_DIR}/../deps/build-all-deps.sh" --all
+else
+    log_info "Skipping dependencies (--skip-deps specified)"
+fi
+
+# Step 3: Check if already built (only relevant with --no-clean)
+if [ $NO_CLEAN -eq 1 ] && check_stamp "${KICAD_STAMP}"; then
+    log_info "KiCad PCBnew already built, skipping..."
+    exit 0
+fi
+
+# Step 4: Verify wxWidgets is built
+if [ ! -f "${WX_BUILD}/lib/libwx_baseu-3.2.a" ]; then
+    log_error "wxWidgets not found. Please build wxWidgets first with:"
+    log_error "  ./scripts/build-wxuniversal-wasm.sh"
+    exit 1
+fi
+
+log_info "Building KiCad PCBnew ${KICAD_VERSION} for WASM..."
+
+# Step 5: Set build type
+if [ $DEBUG -eq 1 ]; then
+    BUILD_TYPE="Debug"
+    EXTRA_FLAGS="-g -O0"
+else
+    BUILD_TYPE="Release"
+    EXTRA_FLAGS="-O2"
+fi
+
+# Step 6: Create build directory
+mkdir -p "${KICAD_BUILD}"
+cd "${KICAD_BUILD}"
+
+# Step 7: Configure KiCad with CMake
+# We use CMAKE_MODULE_PATH to inject our compatibility layer
+log_info "Configuring KiCad with CMake..."
+emcmake cmake "${KICAD_DIR}" \
+    -DCMAKE_BUILD_TYPE=${BUILD_TYPE} \
+    -DCMAKE_INSTALL_PREFIX="${SYSROOT}" \
+    -DCMAKE_MODULE_PATH="${WASM_LAYER}/cmake" \
+    -DCMAKE_POLICY_VERSION_MINIMUM=3.5 \
+    -DCMAKE_CXX_FLAGS="${EXTRA_FLAGS} -pthread -DKICAD_USE_PLATFORM_WASM=1 -I${SYSROOT}/include" \
+    -DCMAKE_C_FLAGS="${EXTRA_FLAGS} -pthread -I${SYSROOT}/include" \
+    -DCMAKE_EXE_LINKER_FLAGS="-pthread -sASYNCIFY=1 -sASYNCIFY_STACK_SIZE=65536 -sUSE_PTHREADS=1 -sPTHREAD_POOL_SIZE=4 -sALLOW_MEMORY_GROWTH=1 -sINITIAL_MEMORY=256MB -sMAXIMUM_MEMORY=4GB -L${SYSROOT}/lib" \
+    -DCMAKE_PREFIX_PATH="${SYSROOT};${WX_BUILD}" \
+    -DwxWidgets_CONFIG_EXECUTABLE="${WX_BUILD}/wx-config" \
+    \
+    -DKICAD_BUILD_QA_TESTS=OFF \
+    -DKICAD_SCRIPTING=OFF \
+    -DKICAD_SCRIPTING_PYTHON3=OFF \
+    -DKICAD_SCRIPTING_WXPYTHON=OFF \
+    -DKICAD_SPICE=OFF \
+    -DKICAD_USE_OCC=OFF \
+    -DKICAD_USE_EGL=OFF \
+    -DKICAD_USE_BUNDLED_GLEW=ON \
+    \
+    -DZSTD_ROOT="${SYSROOT}" \
+    -DZSTD_INCLUDE_DIR="${SYSROOT}/include" \
+    -DZSTD_LIBRARY="${SYSROOT}/lib/libzstd.a" \
+    -DGLM_INCLUDE_DIR="${SYSROOT}/include" \
+    \
+    -DBUILD_GITHUB_PLUGIN=OFF \
+    -DKICAD_PCM=OFF
+
+# Step 8: Build pcbnew target
+log_info "Building pcbnew..."
+JOBS=${JOBS:-$(sysctl -n hw.ncpu 2>/dev/null || nproc 2>/dev/null || echo 4)}
+emmake make -j${JOBS} pcbnew
+
+# Step 9: Create stamp file
+create_stamp "${KICAD_STAMP}"
+log_info "KiCad PCBnew build complete!"
+log_info "Output: ${KICAD_BUILD}/pcbnew/pcbnew.js"