Add KiCad PCBnew WASM build support and documentation

Build infrastructure:
- Update build-pcbnew.sh with stub library compilation
- Update build-wxuniversal-wasm.sh with library symlinks and stubs
- Add stub libraries for libgit2 and curl (network ops via JS)
- Add WASM-specific CMake Find modules

Documentation:
- Add KICAD_WASM_BUILD.md with complete modification list
- Document 68 KiCad files modified for WASM support
- Document disabled features and reasons
- Document stub libraries and wxWidgets changes

Submodule updates:
- kicad: Add WASM/Emscripten build support (wasm-port branch)
- wxwidgets: Add KiCad compatibility fixes

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

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

scripts/deps/build-ngspice.sh

@@ -58,15 +58,18 @@ export CFLAGS="-pthread"
 export CXXFLAGS="-pthread"
 export LDFLAGS="-pthread"
 
-# Configure ngspice as a shared library for KiCad integration
+# Configure ngspice as a static library for WASM
+# Note: --with-ngshared requires shared libs which WASM doesn't support
+# We build static lib instead
 emconfigure "${NGSPICE_DIR}/configure" \
     --prefix="${SYSROOT}" \
     --host=wasm32-unknown-emscripten \
     --build=$(uname -m)-linux-gnu \
-    --enable-shared \
-    --with-ngshared \
+    --disable-shared \
+    --enable-static \
     --disable-debug \
     --disable-dependency-tracking \
+    --disable-openmp \
     --enable-cider \
     --enable-xspice \
     --without-x \