feat: docker & build

dockerfiles/Dockerfile.dev

@@ -0,0 +1,23 @@
+# syntax=docker/dockerfile:1
+# DEV image: source bind-mounted by compose, rsbuild dev server with HMR.
+# node_modules lives in a named volume (see compose) so the host dir never
+# shadows the container install. Build context = mcma-webui/.
+FROM node:22-slim
+
+# `modern-sk` is a git dependency (git+https://...) — npm needs git to fetch it.
+RUN apt-get update \
+    && apt-get install -y --no-install-recommends git \
+    && rm -rf /var/lib/apt/lists/*
+
+WORKDIR /app
+
+COPY package.json package-lock.json modern-sk-*.tgz ./
+RUN npm ci
+
+COPY . .
+
+EXPOSE 3000
+
+# host 0.0.0.0 + HMR client port come from env (RSBUILD_* in compose).
+# `--open` is dropped on purpose: no browser in a container.
+CMD ["npx", "rsbuild", "dev"]