chore: separate Docker build workflow

.github/workflows/build.yml

@@ -19,24 +19,4 @@ jobs:
             - run: cp config.json.example config.json
             - run: echo '{"version":"","buildLabel":"","matchmakingBuildId":""}' > static/data/buildConfig.json
             - run: npm run build
-            - run: npm run lint
-    docker:
-        runs-on: ubuntu-latest
-        if: github.event_name == 'push' && github.ref == 'refs/heads/main'
-        steps:
-            - name: Set up Docker buildx
-              uses: docker/setup-buildx-action@v3
-            - name: Log in to container registry
-              uses: docker/login-action@v3
-              with:
-                registry: ghcr.io
-                username: ${{ github.actor }}
-                password: ${{ secrets.GITHUB_TOKEN }}
-            - name: Build and push
-              uses: docker/build-push-action@v6
-              with:
-                platforms: linux/amd64,linux/arm64
-                push: true
-                tags: |
-                  ghcr.io/${{ github.repository }}:latest
-                  ghcr.io/${{ github.repository}}:${{ github.sha }}
+            - run: npm run lint

.github/workflows/docker.yml

@@ -0,0 +1,26 @@
+name: Build Docker image
+on:
+  push:
+    branches:
+      - main
+    pull_request: {}
+jobs:
+    docker:
+        runs-on: ubuntu-latest
+        steps:
+            - name: Set up Docker buildx
+              uses: docker/setup-buildx-action@v3
+            - name: Log in to container registry
+              uses: docker/login-action@v3
+              with:
+                registry: ghcr.io
+                username: ${{ github.actor }}
+                password: ${{ secrets.GITHUB_TOKEN }}
+            - name: Build and push
+              uses: docker/build-push-action@v6
+              with:
+                platforms: linux/amd64,linux/arm64
+                push: true
+                tags: |
+                  ghcr.io/${{ github.repository }}:latest
+                  ghcr.io/${{ github.repository}}:${{ github.sha }}