Add multi-platform Docker build and publish workflow (#2)

* Add GitHub Actions workflow to build and publish multi-platform Docker image

Agent-Logs-Url: https://github.com/ChicoState/cpp-container/sessions/361bd5c1-79c2-4252-97eb-551e24eb2785

Co-authored-by: kbuffardi <8324410+kbuffardi@users.noreply.github.com>

* Update action versions

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: kbuffardi <8324410+kbuffardi@users.noreply.github.com>
Co-authored-by: Kevin Buffardi <kbuffardi@csuchico.edu>

Author: Copilot

.github/workflows/docker-publish.yml

@@ -0,0 +1,36 @@
+name: Build and Publish Docker Image
+
+on:
+  push:
+    branches:
+      - main
+  workflow_dispatch:
+
+jobs:
+  build-and-push:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v6
+
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v4
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v4
+
+      - name: Log in to Docker Hub
+        uses: docker/login-action@v4
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+
+      - name: Build and push
+        uses: docker/build-push-action@v7
+        with:
+          context: .
+          platforms: linux/amd64,linux/arm64
+          push: true
+          tags: kbuffardi/cpp-container:latest