feat: implement dcutr example and release automation

Author: fbozic

.github/workflows/release-dcutr-example.yml

@@ -0,0 +1,73 @@
+name: Build and release dcutr example
+on:
+  push:
+    branches:
+      - master
+      - feat/dcutr-example
+permissions: write-all
+jobs:
+  metadata:
+    name: Get release metadata
+    runs-on: ubuntu-latest
+    outputs:
+      version: ${{ steps.get_version.outputs.version }}
+      release_exists: ${{ steps.check_release.outputs.exists }}
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Get version
+        id: get_version
+        working-directory: examples/dcutr
+        run: echo "version=dcutr-example-$(cargo read-manifest | jq -r '.version')" >> $GITHUB_OUTPUT
+
+      - name: Check if release exists
+        id: check_release
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          RELEASE_URL=$(curl --silent "https://api.github.com/repos/calimero-network/relay-server/releases/tags/${{ steps.get_version.outputs.version }}" \
+            -H "Authorization: Bearer ${{ secrets.GITHUB_TOKEN }}" \
+            -H "Accept: application/vnd.github.v3+json" | jq -r '.url')
+          if [[ "$RELEASE_URL" != "null" ]]; then
+            echo "exists=true" >> $GITHUB_OUTPUT
+          else
+            echo "exists=false" >> $GITHUB_OUTPUT
+          fi
+
+  release:
+    name: Build and release
+    runs-on: ubuntu-latest
+    needs: metadata
+    if: needs.metadata.outputs.release_exists == 'false'
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Install cross
+        working-directory: examples/dcutr
+        run: cargo install cross --version 0.2.5
+
+      - name: Build for Intel Linux
+        working-directory: examples/dcutr
+        run: cargo build --release --target=x86_64-unknown-linux-gnu
+
+      - name: Build for Aarch Linux
+        working-directory: examples/dcutr
+        run: cross build --release --target=aarch64-unknown-linux-gnu
+
+      - name: Create artifacts directory
+        working-directory: examples/dcutr
+        run: |
+          mkdir -p artifacts
+          cp target/x86_64-unknown-linux-gnu/release/dcutr-example artifacts/dcutr-example-x86_64-unknown-linux
+          cp target/aarch64-unknown-linux-gnu/release/dcutr-example artifacts/dcutr-example-aarch64-unknown-linux
+
+      - name: Create GitHub Release
+        uses: softprops/action-gh-release@v2
+        with:
+          tag_name: ${{ needs.metadata.outputs.version }}
+          files: |
+            examples/dcutr/artifacts/*
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}