Fix Asyncify and improve build process

Build system improvements:
- Add wasm-opt stub for Docker build to bypass asyncify in container
- Add apply-asyncify.sh script for host-side asyncify transformation
- Update build-pcbnew.sh to install wasm-opt stub and add EXPORTED_RUNTIME_METHODS
- Add --with-zlib=sys to wxWidgets configure for proper zlib linking
- Improve update-baseline-screenshots.sh to only copy new/significantly changed files

wxWidgets submodule update:
- Fix EM_JS to EM_ASYNC_JS for proper Asyncify registration

Test updates:
- Add new baseline screenshots for bitmapbuttons, dnd, gridrenderers, printpreview, specialized tests
- Add kicad-pcbnew initial screenshot
- Fix wxgrid-controls.png and wxgrid-dedicated-page.png (were showing errors)

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

docker/build.sh

@@ -11,11 +11,6 @@ set -e
 
 cd "$(dirname "$0")/.."
 
-# Get wasm-opt (downloads Binaryen v121 if not cached)
-echo "Checking wasm-opt..."
-WASM_OPT=$(./scripts/common/get-wasm-opt.sh)
-echo "Using: ${WASM_OPT}"
-
 # Start container if not running
 docker compose -f docker/docker-compose.yml up -d
 
@@ -29,21 +24,8 @@ docker compose -f docker/docker-compose.yml exec kicad-wasm-builder \
     bash -c "mkdir -p /workspace/output && cp /workspace/build-wasm/kicad-pcbnew/pcbnew/pcbnew.{js,wasm,wasm.map,worker.js} /workspace/output/ 2>/dev/null || cp /workspace/build-wasm/kicad-pcbnew/pcbnew/pcbnew.{js,wasm} /workspace/output/"
 
 # Apply asyncify transformation on host
-# This is done on the host because wasm-opt --asyncify needs 50GB+ RAM for KiCad,
-# which exceeds typical Docker memory limits
-echo ""
-echo "Applying asyncify transformation on host..."
-echo "This may take several minutes and use significant RAM..."
-
-# Asyncify import patterns (functions that trigger async suspension)
-# - env.invoke_* : Exception handling trampolines
-# - env.__asyncjs__* : EM_ASYNC_JS functions
-ASYNCIFY_IMPORTS="env.invoke_*,env.__asyncjs__*"
-
-"${WASM_OPT}" --asyncify \
-    --pass-arg=asyncify-imports@${ASYNCIFY_IMPORTS} \
-    --pass-arg=asyncify-propagate-addlist \
-    output/pcbnew.wasm -o output/pcbnew.wasm
+# This is done on the host because wasm-opt --asyncify needs significant RAM
+./scripts/common/apply-asyncify.sh output/pcbnew.wasm output/pcbnew.wasm
 
 echo ""
 echo "Build complete. Output files in ./output/"