Fix wxWidgets WASM rendering and add comprehensive tests

- Update wxwidgets submodule with bitmap, template, and listbox fixes
- Add pcre2 include path to build script
- Add comprehensive UI interaction test covering all tabs
- Update test app with full control demonstration
- Add Makefile.wasm with HEAP exports for Emscripten
- Fix .gitignore to not ignore Makefile.wasm

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

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

scripts/build-wxuniversal-wasm.sh

@@ -47,8 +47,10 @@ echo "=== Configuring ==="
 
 # Set flags for Emscripten compatibility
 # Z_HAVE_UNISTD_H ensures zlib includes <unistd.h> for read/write/lseek
+# Include pcre2 headers from the build directory (generated during configure)
+PCRE2_INCLUDE="$BUILD_DIR/3rdparty/pcre/src"
 export CFLAGS="-DZ_HAVE_UNISTD_H=1"
-export CXXFLAGS="-DZ_HAVE_UNISTD_H=1"
+export CXXFLAGS="-DZ_HAVE_UNISTD_H=1 -I$PCRE2_INCLUDE"
 
 emconfigure "$WX_SOURCE/configure" \
     --host=emscripten \