fix(ci): automate release branch publishing

.github/workflows/publish.yml

@@ -1,20 +1,79 @@
-name: Publish to Crates.io
+name: Release and Publish
 
 on:
-  release:
-    types: [published]
+  push:
+    branches:
+      - release
+
+permissions:
+  contents: write
 
 jobs:
   publish:
-    name: Publish on release
+    name: Create release and publish crate
     runs-on: ubuntu-latest
+    env:
+      GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+      CARGO_REGISTRY_TOKEN: ${{ secrets.CARGO_REGISTRY_TOKEN }}
+
     steps:
-      - uses: actions/checkout@v4
-      - uses: actions-rs/toolchain@v1
+      - name: Checkout code
+        uses: actions/checkout@v4
         with:
-          toolchain: stable
-          override: true
+          fetch-depth: 0
+
+      - name: Install Rust toolchain
+        uses: dtolnay/rust-toolchain@stable
+
+      - name: Read package metadata
+        shell: bash
+        run: |
+          python - <<'PY' >> "$GITHUB_ENV"
+          import pathlib
+          import tomllib
+
+          cargo_toml = tomllib.loads(pathlib.Path("Cargo.toml").read_text(encoding="utf-8"))
+          package = cargo_toml["package"]
+          name = package["name"]
+          version = package["version"]
+
+          print(f"PACKAGE_NAME={name}")
+          print(f"PACKAGE_VERSION={version}")
+          print(f"RELEASE_TAG={name}-v{version}")
+          print(f"RELEASE_TITLE={name} v{version}")
+          PY
+
+      - name: Create GitHub release
+        shell: bash
+        run: |
+          if gh release view "$RELEASE_TAG" >/dev/null 2>&1; then
+            echo "Release $RELEASE_TAG already exists."
+          else
+            gh release create "$RELEASE_TAG" \
+              --target "$GITHUB_SHA" \
+              --title "$RELEASE_TITLE" \
+              --generate-notes
+          fi
+
+      - name: Check crates.io for published version
+        id: crates
+        shell: bash
+        run: |
+          status="$(curl -s -o /dev/null -w "%{http_code}" "https://crates.io/api/v1/crates/$PACKAGE_NAME/$PACKAGE_VERSION")"
+
+          case "$status" in
+            200)
+              echo "already_published=true" >> "$GITHUB_OUTPUT"
+              ;;
+            404)
+              echo "already_published=false" >> "$GITHUB_OUTPUT"
+              ;;
+            *)
+              echo "Unexpected crates.io response: $status"
+              exit 1
+              ;;
+          esac
+
       - name: Publish to crates.io
-        run: cargo publish --token ${{ secrets.CARGO_REGISTRY_TOKEN }}
-        env:
-          CARGO_REGISTRY_TOKEN: ${{ secrets.CARGO_REGISTRY_TOKEN }}
+        if: steps.crates.outputs.already_published != 'true'
+        run: cargo publish --locked --package "$PACKAGE_NAME" --token "$CARGO_REGISTRY_TOKEN"