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>

tests/wasm-app/minimal_test.html

@@ -46,6 +46,12 @@
     var statusElement = document.getElementById('progress-text');
     var progressElement = document.getElementById('progress-bar-position');
 
+    var showError = function(msg) {
+      console.error(msg);
+      statusElement.innerHTML = msg;
+      statusElement.style.color = 'red';
+    };
+
     var createCanvas = function () {
       var canvas = document.createElement('canvas');
       canvas.id = 'canvas';