Add publish-snapshot workflow for GitHub Packages snapshot publishing

Author: edburns

.github/workflows/publish-snapshot.yml

@@ -0,0 +1,54 @@
+name: Publish Snapshot to GitHub Packages
+
+env:
+    HUSKY: 0
+
+on:
+    workflow_dispatch:
+
+permissions:
+    contents: read
+    packages: write
+
+concurrency:
+    group: publish-snapshot
+    cancel-in-progress: false
+
+jobs:
+    publish-snapshot:
+        name: Publish SNAPSHOT to GitHub Packages
+        runs-on: ubuntu-latest
+        steps:
+            - uses: actions/checkout@v6
+              with:
+                  fetch-depth: 0
+
+            - uses: ./.github/actions/setup-copilot
+
+            - name: Set up JDK 17
+              uses: actions/setup-java@v5
+              with:
+                  java-version: "17"
+                  distribution: "temurin"
+                  cache: "maven"
+                  server-id: github
+                  server-username: PACKAGES_USERNAME
+                  server-password: PACKAGES_TOKEN
+
+            - name: Verify version is a SNAPSHOT
+              run: |
+                  VERSION=$(mvn help:evaluate -Dexpression=project.version -q -DforceStdout)
+                  echo "Publishing version: $VERSION"
+                  if [[ "$VERSION" != *"-SNAPSHOT" ]]; then
+                    echo "ERROR: This workflow only publishes SNAPSHOT versions. Current version: $VERSION"
+                    exit 1
+                  fi
+                  echo "### Snapshot Publish" >> $GITHUB_STEP_SUMMARY
+                  echo "- **Version:** $VERSION" >> $GITHUB_STEP_SUMMARY
+                  echo "- **Repository:** GitHub Packages (github/copilot-sdk-java)" >> $GITHUB_STEP_SUMMARY
+
+            - name: Deploy Snapshot
+              run: mvn -B deploy -DskipTests
+              env:
+                  PACKAGES_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+                  PACKAGES_USERNAME: ${{ github.actor }}