first try of automated docker builds

.gitea/workflows/backed_build-image.yaml

@@ -0,0 +1,30 @@
+on:
+  pull_request:
+    branches:
+      - main
+
+name: Build and push docker image
+
+jobs:
+  build:
+    name: Build
+    runs-on: ubuntu-latest
+    steps:
+
+    - uses: https://gitea.com/actions/checkout@v4
+    
+    - name: Login to Docker Registry
+      uses: docker/login-action@v3
+      with:
+        registry: git.kluster.moll.re
+        username: ${{ gitea.repository_owner }}
+        password: ${{ secrets.GITEA_TOKEN}}
+
+    - name: Set up Docker Buildx
+      uses: docker/setup-buildx-action@v3
+
+    - name: Build and push
+      uses: docker/build-push-action@v5
+      with:
+        context: backend
+        tags: git.kluster.moll.re/renoll/fast_network_navigation/backend:latest

.gitea/workflows/frontend_build-android.yaml

@@ -8,7 +8,7 @@ name: Build and release APK
 jobs:
   build:
     name: Build APK
-    runs-on: k8s
+    runs-on: ubuntu-latest
     steps:
 
     - name: Install prerequisites