add basic build step to validate DockerFile

.gitea/workflows/build.yaml

@@ -0,0 +1,21 @@
+# .gitea/workflows/build.yml
+name: Build Validation
+
+on:
+  push:
+    branches:
+      - '**'
+  pull_request:
+    branches: [main]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+      
+      - name: Build Docker Image
+        run: |
+          docker build -t ${{ secrets.LOCAL_INSTANCE_IP }}/${{ secrets.DOCKER_USERNAME }}/devcontainer:latest -f Dockerfile .
+