Add docker build environment

docker/cpp-mingw-vcpkg/Dockerfile.txt

@@ -0,0 +1,24 @@
+FROM ubuntu:24.04
+
+ENV DEBIAN_FRONTEND=noninteractive
+ENV VCPKG_ROOT=/opt/vcpkg
+ENV PATH="${VCPKG_ROOT}:${PATH}"
+
+RUN apt-get update && apt-get install -y \
+    build-essential \
+    mingw-w64 \
+    cmake \
+    ninja-build \
+    git \
+    curl \
+    zip \
+    unzip \
+    tar \
+    pkg-config \
+    ca-certificates \
+    && rm -rf /var/lib/apt/lists/*
+
+RUN git clone https://github.com/microsoft/vcpkg.git ${VCPKG_ROOT} \
+    && ${VCPKG_ROOT}/bootstrap-vcpkg.sh
+
+WORKDIR /workspace