ci: add copilot-setup-steps workflow for coding-agent parity

.github/workflows/copilot-setup-steps.yml

@@ -0,0 +1,46 @@
+---
+name: "Copilot Setup Steps"
+
+# Provision the .NET toolchain the Copilot coding agent needs before it starts,
+# mirroring the sibling templates (go-template, platform-template) so adopters
+# get a working agent environment out of the box. The setup runs on changes to
+# this file (and on manual dispatch) so it is validated like any other workflow.
+on:
+  workflow_dispatch:
+  push:
+    paths:
+      - .github/workflows/copilot-setup-steps.yml
+  pull_request:
+    paths:
+      - .github/workflows/copilot-setup-steps.yml
+
+permissions: {}
+
+jobs:
+  # The job MUST be called `copilot-setup-steps` or Copilot will not pick it up.
+  copilot-setup-steps:
+    runs-on: ubuntu-latest
+
+    permissions:
+      contents: read
+
+    steps:
+      - name: 🛡️ Harden runner
+        uses: step-security/harden-runner@9af89fc71515a100421586dfdb3dc9c984fbf411 # v2.19.4
+        with:
+          egress-policy: audit
+
+      - name: 📑 Checkout
+        uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6.0.3
+        with:
+          persist-credentials: false
+
+      - name: ⚙️ Set up .NET
+        uses: actions/setup-dotnet@9a946fdbd5fb07b82b2f5a4466058b876ab72bb2 # v5.3.0
+        with:
+          # Track global.json so the Copilot toolchain never drifts from the SDK
+          # floor (the .NET parity to go-template's `go-version-file: go.mod`).
+          global-json-file: global.json
+
+      - name: 📦 Restore dependencies
+        run: dotnet restore Example.slnx