Add README and CI pipeline for Docker image build and push to Gitea registry

.gitea/workflows/ci.yml

@@ -0,0 +1,50 @@
+name: Build and Push Sandbox Base Image
+
+on:
+  push:
+    branches:
+      - main
+    tags:
+      - 'v*'
+  pull_request:
+    branches:
+      - main
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v3
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Log in to Gitea Container Registry
+        uses: docker/login-action@v3
+        with:
+          registry: git.danhenry.dev:5050
+          username: ${{ secrets.REGISTRY_USERNAME }}
+          password: ${{ secrets.REGISTRY_PASSWORD }}
+
+      - name: Build and push
+        id: build
+        uses: docker/build-push-action@v5
+        with:
+          context: .
+          push: ${{ github.event_name != 'pull_request' }}
+          tags: |
+            git.danhenry.dev:5050/TheLab/sandbox-base-image:${{ github.sha }}
+            git.danhenry.dev:5050/TheLab/sandbox-base-image:latest
+          cache-from: type=registry,ref=git.danhenry.dev:5050/TheLab/sandbox-base-image:latest
+          cache-to: type=registry,ref=git.danhenry.dev:5050/TheLab/sandbox-base-image:latest,mode=max
+          platforms: linux/amd64,linux/arm64
+
+      - name: Tag and push stable (main only)
+        if: github.ref == 'refs/heads/main' && github.event_name != 'pull_request'
+        run: |
+          docker tag git.danhenry.dev:5050/TheLab/sandbox-base-image:${{ github.sha }} git.danhenry.dev:5050/TheLab/sandbox-base-image:stable
+          docker push git.danhenry.dev:5050/TheLab/sandbox-base-image:stable