🔨 サンプルコード統一用workflowを追加

Author: hi2ma-bu4

.github/workflows/notify-showcase.yml

@@ -0,0 +1,16 @@
+name: Notify Showcase
+
+on:
+    push:
+        branches: [main]
+
+jobs:
+    notify-parent:
+        runs-on: ubuntu-latest
+        steps:
+            - name: Dispatch event to RepoShowcase
+              run: |
+                  curl -X POST https://api.github.com/repos/hi2ma-bu4/RepoShowcase/dispatches \
+                  -H "Authorization: token ${{ secrets.SHOWCASE_DISPATCH_TOKEN }}" \
+                  -H "Accept: application/vnd.github.v3+json" \
+                  -d '{"event_type":"child_updated", "client_payload": {"child": "javalibraryscript"}}'