Checkpoint: v4.0 media service, compose deploy, and verified docs

media/Dockerfile

@@ -0,0 +1,17 @@
+FROM golang:1.23-bookworm AS build
+WORKDIR /src
+COPY go.mod ./
+RUN go mod download
+COPY . .
+RUN CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -o /out/media-service ./main.go
+
+FROM debian:bookworm-slim
+WORKDIR /app
+RUN apt-get update \
+  && apt-get install -y --no-install-recommends ca-certificates ffmpeg \
+  && rm -rf /var/lib/apt/lists/*
+COPY --from=build /out/media-service /usr/local/bin/media-service
+ENV MEDIA_ADDR=:8081
+ENV MEDIA_DATA_DIR=/data/media
+EXPOSE 8081
+CMD ["media-service"]