chore(release): create pr for notes on release (#75)

---------

Co-authored-by: Copilot <[email protected]>

Author: arrowplum

.github/workflows/release-changelog.yaml

@@ -0,0 +1,41 @@
+name: Release Changelog PR
+on:
+  release:
+    types: [published]
+  workflow_dispatch:
+
+permissions:
+  contents: write
+  pull-requests: write
+
+jobs:
+  create-changelog-pr:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v5
+        with:
+          fetch-depth: 0
+          fetch-tags: true
+          ref: main
+
+      - uses: actions/setup-node@v6
+        with:
+          node-version: 22
+
+      - name: Update CHANGELOG.md
+        run: |
+          npx -y conventional-changelog-cli@5 \
+            -p conventionalcommits \
+            -i CHANGELOG.md -s
+
+      - name: Open PR with changelog
+        uses: peter-evans/create-pull-request@271a8d0340265f705b14b6d32b9829c1cb33d45e # v7.0.8
+        with:
+          token: ${{ secrets.GITHUB_TOKEN }}
+          base: main
+          branch: chore/changelog-${{ github.event.release.tag_name }} # created if missing
+          commit-message: "docs(changelog): release notes for ${{ github.event.release.tag_name }}"
+          title: "docs(changelog): release notes for ${{ github.event.release.tag_name }}"
+          body: "Automated changelog update for ${{ github.event.release.tag_name }}."
+          add-paths: |
+            CHANGELOG.md