feat: add upstream sync workflow

.github/workflows/sync-upstream.yml

@@ -0,0 +1,66 @@
+name: Sync with Upstream
+
+on:
+  schedule:
+    # Weekly on Monday at 6 AM UTC
+    - cron: '0 6 * * 1'
+  workflow_dispatch:
+
+permissions:
+  contents: write
+  pull-requests: write
+
+jobs:
+  sync-upstream:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Add upstream remote
+        run: |
+          git remote add upstream https://github.com/alexandrevilain/temporal-operator.git || true
+          git fetch upstream
+
+      - name: Check for upstream changes
+        id: check-changes
+        run: |
+          # Compare local main with upstream main
+          LOCAL_SHA=$(git rev-parse HEAD)
+          UPSTREAM_SHA=$(git rev-parse upstream/main)
+
+          if [ "$LOCAL_SHA" = "$UPSTREAM_SHA" ]; then
+            echo "No changes from upstream"
+            echo "has_changes=false" >> $GITHUB_OUTPUT
+          else
+            echo "Upstream has changes"
+            echo "has_changes=true" >> $GITHUB_OUTPUT
+          fi
+
+      - name: Merge upstream changes
+        if: steps.check-changes.outputs.has_changes == 'true'
+        run: |
+          git config user.name "github-actions[bot]"
+          git config user.email "github-actions[bot]@users.noreply.github.com"
+          git merge upstream/main --no-edit --allow-unrelated-histories || true
+
+      - name: Create Pull Request
+        if: steps.check-changes.outputs.has_changes == 'true'
+        uses: peter-evans/create-pull-request@v6
+        with:
+          token: ${{ secrets.GITHUB_TOKEN }}
+          commit-message: "chore: sync with upstream temporal-operator"
+          branch: chore/sync-upstream
+          delete-branch: true
+          title: "chore: sync with upstream temporal-operator"
+          body: |
+            This PR syncs changes from the upstream repository [alexandrevilain/temporal-operator](https://github.com/alexandrevilain/temporal-operator).
+
+            **Automated sync triggered by GitHub Actions.**
+
+            Please review the changes carefully before merging.
+          labels: |
+            upstream-sync
+            automated