chore: add Dockerfile and Forgejo CI publish workflow: Dockerfile

Dockerfile

@@ -0,0 +1,37 @@
+# syntax=docker/dockerfile:1
+# Builds the Wild Dragon Restreamer UI:
+#   1. Clone upstream datarhei/restreamer-ui at UPSTREAM_TAG
+#   2. Apply overlay (branding + WebRTC components)
+#   3. yarn build
+#   4. Serve with Caddy
+
+ARG UPSTREAM_TAG=v1.14.0
+ARG NODE_VERSION=20
+
+# ── Build ─────────────────────────────────────────────────────────────────────
+FROM node:${NODE_VERSION}-alpine AS ui-builder
+
+ARG UPSTREAM_TAG
+
+RUN apk add --no-cache git
+
+RUN git clone --depth 1 --branch ${UPSTREAM_TAG} \
+        https://github.com/datarhei/restreamer-ui.git /ui
+
+WORKDIR /ui
+RUN yarn install --frozen-lockfile
+
+COPY overlay/ /overlay/
+COPY apply-overlay.sh /apply-overlay.sh
+RUN sh /apply-overlay.sh
+
+ENV PUBLIC_URL=./
+RUN yarn build
+
+# ── Serve ─────────────────────────────────────────────────────────────────────
+FROM caddy:2-alpine
+
+COPY --from=ui-builder /ui/build/ /srv/
+COPY Caddyfile /etc/caddy/Caddyfile
+
+EXPOSE 3000