adds build workflow

.github/workflows/build.yml

@@ -0,0 +1,51 @@
+name: build
+
+on:
+    push:
+        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
+              id: buildx
+              uses: docker/setup-buildx-action@v3
+
+            - name: Cache Docker layers
+              uses: actions/cache@v4
+              with:
+                  path: /tmp/.buildx-cache
+                  key: ${{ runner.os }}-buildx-${{ github.sha }}
+                  restore-keys: |
+                      ${{ runner.os }}-buildx-
+
+            - name: Login to GHC
+              uses: docker/login-action@v3
+              with:
+                  registry: ghcr.io
+                  username: ${{ github.actor }}
+                  password: ${{ secrets.GHCR_TOKEN }}
+
+            - name: Build and push
+              uses: docker/build-push-action@v5
+              with:
+                  context: .
+                  push: true
+                  platforms: linux/amd64
+                  tags: |
+                      ghcr.io/designunit/korsakov:latest
+                  cache-from: type=local,src=/tmp/.buildx-cache
+                  cache-to: type=local,dest=/tmp/.buildx-cache-new
+
+            - name: Move cache
+              run: |
+                  rm -rf /tmp/.buildx-cache
+                  mv /tmp/.buildx-cache-new /tmp/.buildx-cache