Add Docker build + Gitea Actions CI for self-hosting

- next.config: output 'standalone' for a self-contained server bundle
- Dockerfile: multi-stage Next.js build (node:22-alpine)
- .gitea/workflows/deploy.yml: build + push to the Gitea registry

.gitea/workflows/deploy.yml

@@ -0,0 +1,25 @@
+name: build-and-publish
+on:
+  push:
+    branches: [master, main]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Log in to the Gitea container registry
+        run: echo "${{ secrets.REGISTRY_TOKEN }}" | docker login git.thebennett.net -u "${{ secrets.REGISTRY_USER }}" --password-stdin
+
+      - name: Build image
+        run: |
+          docker build \
+            -t git.thebennett.net/austin/itsthevine:latest \
+            -t git.thebennett.net/austin/itsthevine:${{ github.sha }} .
+
+      - name: Push image
+        run: |
+          docker push git.thebennett.net/austin/itsthevine:latest
+          docker push git.thebennett.net/austin/itsthevine:${{ github.sha }}