ci: add release-please for automated releases

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.github/workflows/release-please.yml

@@ -0,0 +1,19 @@
+name: Release Please
+
+on:
+  push:
+    branches:
+      - main
+
+permissions:
+  contents: write
+  pull-requests: write
+
+jobs:
+  release-please:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: googleapis/release-please-action@v4
+        with:
+          config-file: release-please-config.json
+          manifest-file: .release-please-manifest.json