refactor: migrate browser gateway to native xvfb

Dockerfile

@@ -15,17 +15,13 @@ COPY internal/ ./internal/
 RUN CGO_ENABLED=0 go build -buildvcs=false -trimpath -ldflags='-s -w' -o /out/control-plane ./cmd/control-plane
 
 FROM python:3.13-alpine@sha256:7415fbc3c9e4979cc717d92377ab2bc7b2b4a2af1ac03cc52b5f3f88efedaf3a
-COPY requirements-gateway.lock /tmp/requirements-gateway.lock
 RUN apk add --no-cache ffmpeg \
-    && python -m pip install --no-cache-dir -r /tmp/requirements-gateway.lock \
     && addgroup -g 65532 app && adduser -D -u 65532 -G app app \
     && install -d -o app -g app -m 0700 /var/lib/creatorhub/credentials /var/lib/creatorhub/materials
 WORKDIR /app
 COPY --from=go /out/control-plane /app/
-COPY cmd/__init__.py /app/cmd/__init__.py
-COPY cmd/docker_gateway /app/cmd/docker_gateway
 COPY --from=web /src/web/dist /app/web
 USER 65532:65532
 ENV WEB_DIR=/app/web
-EXPOSE 8080 8081
+EXPOSE 8080
 CMD ["/app/control-plane"]