add workflows

.github/workflows/hassfest.yaml

@@ -0,0 +1,16 @@
+name: Validate with hassfest
+
+on:
+  push:
+  pull_request:
+  workflow_dispatch:
+  schedule:
+    - cron:  '0 6 * * 6'  
+
+jobs:
+  validate-hassfest:
+    runs-on: "ubuntu-latest"
+    steps:
+        - uses: "actions/checkout@v4"
+        - name: HA validation
+          uses: "home-assistant/actions/hassfest@master"