chore: add docker image build and publish workflow

Author: zachsmith1

.dockerignore

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+.git
+.github
+target
+ui/node_modules
+ui/target
+ui/dist
+ui/.dioxus
+**/*.log
+**/*.tmp

.github/workflows/publish-docker.yml

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+name: Publish Docker Image
+
+on:
+  pull_request:
+  push:
+    branches:
+      - main
+  release:
+    types:
+      - published
+
+permissions:
+  contents: read
+  packages: write
+
+jobs:
+  publish:
+    uses: datum-cloud/actions/.github/workflows/publish-docker.yaml@v1
+    with:
+      image-name: datum-iroh-gateway
+    secrets: inherit

Dockerfile

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+FROM rust:1.88-bookworm AS builder
+
+WORKDIR /app
+
+COPY . .
+
+RUN cargo build -p datum-connect --release
+
+FROM debian:bookworm-slim
+
+RUN apt-get update \
+  && apt-get install -y --no-install-recommends ca-certificates \
+  && rm -rf /var/lib/apt/lists/* \
+  && useradd -u 65532 -r -s /usr/sbin/nologin datum
+
+COPY --from=builder /app/target/release/datum-connect /usr/local/bin/datum-connect
+
+USER 65532:65532
+
+ENTRYPOINT ["/usr/local/bin/datum-connect"]
+CMD ["gateway"]