Scaffold vpinball-wasm: Emscripten port of Visual Pinball

Build scripts, CMake/source patches, npm packaging, and a Gitea CI
workflow to compile the real Visual Pinball engine (SDL3 + WebGL2 +
libwinevbs for real VBScript) to WebAssembly.

The patches are validated end-to-end: the patched engine boots in a
real browser, loads a real .vpx table, compiles its real GLSL shaders,
computes environment map radiance, initializes physics, and starts the
VBScript engine, before hanging on the one deliberately-deferred piece
of work (game loop rewrite around emscripten_set_main_loop), documented
in the README's roadmap.

scripts/dev-server.sh

@@ -0,0 +1,16 @@
+#!/usr/bin/env bash
+# Serves dist/ locally for manual browser testing. No COOP/COEP headers are
+# needed since this build is single-threaded (no pthreads/SharedArrayBuffer).
+set -euo pipefail
+
+ROOT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+DIST_DIR="$ROOT_DIR/dist"
+PORT="${1:-8080}"
+
+if [ ! -f "$DIST_DIR/index.html" ] && [ ! -f "$DIST_DIR/vpinball.js" ]; then
+   echo "ERROR: dist/ is empty. Run scripts/build.sh first." >&2
+   exit 1
+fi
+
+echo "Serving $DIST_DIR at http://localhost:$PORT/"
+cd "$DIST_DIR" && python3 -m http.server "$PORT"