feat(release): track prerelease deltas and validate committed notes

- Compare fragment changes with previous beta/RC tags
- Reject stale prerelease notes in CI

.github/workflows/docs-pages.yml

@@ -32,9 +32,11 @@ jobs:
       - name: Guard stable docs tag shape
         id: tag_guard
         if: github.ref_type == 'tag'
+        env:
+          TAG_NAME: ${{ github.ref_name }}
         run: |
-          if [[ ! "${{ github.ref_name }}" =~ ^v[0-9]+\.[0-9]+\.[0-9]+$ ]]; then
-            echo "::notice::Skipping non-stable docs tag ${{ github.ref_name }}"
+          if [[ ! "$TAG_NAME" =~ ^v[0-9]+\.[0-9]+\.[0-9]+$ ]]; then
+            echo "::notice::Skipping non-stable docs tag $TAG_NAME"
             echo "stable_tag=false" >> "$GITHUB_OUTPUT"
             exit 0
           fi