add build script

.github/workflows/build.yaml

@@ -0,0 +1,26 @@
+name: build
+
+on: workflow_dispatch
+
+jobs:
+  docker:
+    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: Build and push
+        uses: docker/build-push-action@v6
+        with:
+          file: ./docker/default.Dockerfile
+          platforms: linux/amd64,linux/arm64,linux/arm/v7
+          push: false
+          tags: sissbruecker/linkding:test
+          target: linkding