feat(ci): add deployment workflow and update Dockerfile

.gitea/workflows/deploy.yml

@@ -0,0 +1,21 @@
+name: Deploy
+on:
+  push:
+    branches:
+      - "main"
+      - "feat/deployment"
+    paths:
+      - "backend/**"
+  
+jobs:
+  build-image:
+    runs-on: ubuntu-latest
+    name: Build Docker Image
+    steps:
+      - uses: actions/checkout@v4
+      - name: Build Image
+        run: docker buildx build -f .docker/Dockerfile -t git.kjan.de/SZUT/casino-backend:latest .
+      - name: Login
+        run: echo ${DOCKER_PASS} | docker login git.kjan.de --username ${DOCKER_USER} --password-stdin
+      - name Push
+        run: docker push git.kja.de/SZUT/casino-backend:latest