feat: Add SPDX header check workflow

Co-authored-by: zccrs <13449038+zccrs@users.noreply.github.com>

Author: Copilot

.github/workflows/spdx-check.yml

@@ -0,0 +1,14 @@
+name: SPDX Header Check
+
+on:
+  pull_request:
+    branches: [main]
+
+jobs:
+  spdx-check:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: zccrs/github-actions-spdx-checker@main
+        with:
+          base: origin/main
+          exclude: 'vendor/**,node_modules/**,3rdparty/**,*.json'