Add push_gem workflow for rubygems/gemstash

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: hsbt

.github/workflows/push_gem.yml

@@ -0,0 +1,46 @@
+name: Publish gem to rubygems.org
+
+on:
+  push:
+    tags:
+      - 'v*'
+
+permissions:
+  contents: read
+
+jobs:
+  push:
+    if: github.repository == 'rubygems/gemstash'
+    runs-on: ubuntu-latest
+
+    environment:
+      name: rubygems.org
+      url: https://rubygems.org/gems/gemstash
+
+    permissions:
+      contents: write
+      id-token: write
+
+    steps:
+      - name: Harden Runner
+        uses: step-security/harden-runner@fa2e9d605c4eeb9fcad4c99c224cee0c6c7f3594 # v2.16.0
+        with:
+          egress-policy: audit
+
+      - uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3 # v6.0.0
+
+      - name: Set up Ruby
+        uses: ruby/setup-ruby@d5126b9b3579e429dd52e51e68624dda2e05be25 # v1.267.0
+        with:
+          bundler-cache: true
+          ruby-version: ruby
+
+      - name: Publish to RubyGems
+        uses: rubygems/release-gem@e9a6361a0b14562539327c2a02373edc56dd3169 # v1.1.4
+
+      - name: Create GitHub release
+        run: |
+          tag_name="$(git describe --tags --abbrev=0)"
+          gh release create "${tag_name}" --verify-tag --generate-notes
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}