Build/test plumbing for the second wxWidgets mode: --dom on
build-wxuniversal-wasm.sh (build-wasm/wxwidgets-dom, no universal,
--disable-tooltips, libwx_wasmu_* stubs) and build-wasm-test.sh
(mirrors sources into tests/apps-dom, PORT=dom). Build script now
reconfigures when Makefile.in or autoconf_inc.m4 regenerate (bakefile
chain). Harness: WX_PORT=dom serves apps-dom, namespaces screenshots
into test-results/dom and logs into logs/wxwidgets/dom; compare/update
screenshot scripts take --port dom with baseline-screenshots-dom.
New port-agnostic boot.spec.ts (green on both ports).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>