ci: add Docker Hub build and push on tag (v*)

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: troke12

.github/workflows/docker-publish.yml

@@ -0,0 +1,54 @@
+name: Build and push to Docker Hub
+
+on:
+  push:
+    tags:
+      - 'v*'
+
+env:
+  REGISTRY: docker.io
+
+jobs:
+  build-and-push:
+    runs-on: ubuntu-latest
+    environment: master
+    permissions:
+      contents: read
+      packages: write
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Log in to Docker Hub
+        uses: docker/login-action@v3
+        with:
+          username: troke12
+          password: ${{ secrets.DOCKER_TOKEN }}
+
+      - name: Extract version tag
+        id: tag
+        run: echo "VERSION=${GITHUB_REF#refs/tags/}" >> $GITHUB_OUTPUT
+
+      - name: Build and push backend
+        uses: docker/build-push-action@v6
+        with:
+          context: ./backend
+          file: ./backend/Dockerfile
+          push: true
+          tags: |
+            troke12/refity-backend:latest
+            troke12/refity-backend:${{ steps.tag.outputs.VERSION }}
+
+      - name: Build and push frontend
+        uses: docker/build-push-action@v6
+        with:
+          context: ./frontend
+          file: ./frontend/Dockerfile
+          push: true
+          tags: |
+            troke12/refity-frontend:latest
+            troke12/refity-frontend:${{ steps.tag.outputs.VERSION }}