📦 build(ci): add build-and-push workflow for docker images

- create a new CI workflow to automate image building and pushing
- trigger workflow on push to main branch
- include steps for checkout, login, build, and push docker images

.forgejo/workflows/build.yml

@@ -0,0 +1,26 @@
+name: build-and-push
+
+on:
+  push:
+    branches:
+      - main
+
+jobs:
+  docker:
+    runs-on: self-hosted
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Login to registry
+        run: echo "${{ secrets.REG_TOKEN }}" | docker login "${{ secrets.REGISTRY }}" -u "${{ secrets.REG_USER }}" --password-stdin
+
+      - name: Build image
+        run: |
+          docker build -t "${{ secrets.REGISTRY_IMAGE }}:${{ github.sha }}" \
+                       -t "${{ secrets.REGISTRY_IMAGE }}:latest" .
+
+      - name: Push image
+        run: |
+          docker push "${{ secrets.REGISTRY_IMAGE }}:${{ github.sha }}"
+          docker push "${{ secrets.REGISTRY_IMAGE }}:latest"