ci: use tag message as release notes body

Extracts annotated tag message via git tag --format and passes
it as body_path to action-gh-release. Fetch-depth: 0 ensures
tag data is available in checkout.

.github/workflows/release.yml

@@ -13,6 +13,8 @@ jobs:
 
     steps:
       - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
 
       - name: Create tarball
         run: |
@@ -22,10 +24,17 @@ jobs:
         run: |
           git archive --format=zip --prefix=passepartout-$(git describe --tags) HEAD -o passepartout.zip
 
+      - name: Extract tag message as release notes
+        run: |
+          git tag -l --format='%(contents)' ${GITHUB_REF#refs/tags/} > /tmp/release-notes.md
+          echo "--- Notes preview ---"
+          head -20 /tmp/release-notes.md
+
       - name: Upload to GitHub Release
         uses: softprops/action-gh-release@v2
         with:
           files: |
             passepartout.tar.gz
             passepartout.zip
+          body_path: /tmp/release-notes.md
           generate_release_notes: true