add workflow to build the latest beta

.gitea/workflows/beta-build.yml

@@ -0,0 +1,35 @@
+name: Beta Docker Build
+
+on:
+  workflow_dispatch:     # Allow manual runs
+
+jobs:
+  build-and-push:
+    steps:
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+      - name: Set up QEMU (for cross-platform builds)
+        uses: docker/setup-qemu-action@v3
+      - name: Login to Docker registry
+        uses: docker/login-action@v3
+        with:
+          registry: git.arinity.org
+          username: matt
+          password: ${{ secrets.DOCKER_PUSH_TOKEN }}
+      - name: Fetch beta.yml and extract version
+        id: fetch_beta_data
+        run: |
+          version=$(curl -sSL https://affirmatech.com/download/meshsense/beta.yml | grep '^version:' | awk '{print $2}')
+          echo "version=$version" >> $GITHUB_OUTPUT
+      - name: Checkout repository
+        uses: actions/checkout@v4
+      - name: Build and push image
+        uses: docker/build-push-action@v5
+        with:
+          context: .
+          file: ./Dockerfile
+          platforms: linux/amd64,linux/arm64
+          push: true
+          build-args: |
+            GIT_REF=v${{ steps.fetch_beta_data.outputs.version }}
+          tags: git.arinity.org/meshtastic-tools/meshsense:beta