Update core library to use real wxBase instead of wx_shim

- Update CMakeLists.txt to link against wxBase WASM build
- Move config.h to wasm-config/ to avoid conflicts with wx headers
- Add build-core-wasm.sh script for reproducible builds
- Core now compiles with actual wxString, wxFile, etc. from wxWidgets

Libraries built:
- libkicad_core_utils.a (34K)
- libkimath.a (969K)
- libsexpr.a (45K)
- libclipper2.a (169K)

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

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

scripts/build-core-wasm.sh

@@ -0,0 +1,53 @@
+#!/bin/bash
+# Build KiCad core library for WebAssembly
+# This builds kimath, sexpr, and core utilities with wxBase
+
+set -e
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+PROJECT_ROOT="$(dirname "$SCRIPT_DIR")"
+BUILD_DIR="$PROJECT_ROOT/build-wasm/core"
+CORE_SOURCE="$PROJECT_ROOT/core"
+
+echo "=== Building KiCad Core for WASM ==="
+echo "Project root: $PROJECT_ROOT"
+echo "Build dir: $BUILD_DIR"
+echo "Core source: $CORE_SOURCE"
+
+# Verify core source exists
+if [ ! -f "$CORE_SOURCE/CMakeLists.txt" ]; then
+    echo "ERROR: Core source not found at $CORE_SOURCE"
+    exit 1
+fi
+
+# Verify wxBase was built
+if [ ! -f "$PROJECT_ROOT/build-wasm/wxwidgets/lib/libwx_baseu-3.2-Emscripten.a" ]; then
+    echo "ERROR: wxBase not built. Run scripts/build-wxbase-wasm.sh first"
+    exit 1
+fi
+
+# Clean if requested (must be before mkdir to properly reset CMake cache)
+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 emcmake
+echo ""
+echo "=== Configuring ==="
+emcmake cmake "$CORE_SOURCE" \
+    -DCMAKE_BUILD_TYPE=Release \
+    -DBUILD_TESTS=OFF
+
+# Build
+echo ""
+echo "=== Building ==="
+emmake make -j$(nproc 2>/dev/null || sysctl -n hw.ncpu)
+
+echo ""
+echo "=== Build complete ==="
+ls -lh "$BUILD_DIR"/*.a 2>/dev/null || echo "Libraries built in $BUILD_DIR"