Update build workflow to publish container image to GitHub registry

.github/workflows/build.yaml

@@ -32,6 +32,9 @@ jobs:
   container-image:
     name: 'Build container image'
     runs-on: ubuntu-24.04
+    permissions:
+      contents: read
+      packages: write
     needs:
       - extract-version
     steps:
@@ -42,18 +45,19 @@ jobs:
           files: '["**/environment.prod.ts"]'
         env:
           TOKEN_APPLICATION_VERSION: "${{ needs.extract-version.outputs.turnierplan_version }}"
-      - name: Login to Docker Hub
+      - name: Login to container registry
         uses: docker/login-action@65b78e6e13532edd9afa3aa52ac7964289d1a9c1
         with:
-          username: ${{ secrets.DOCKER_HUB_USERNAME }}
-          password: ${{ secrets.DOCKER_HUB_PASSWORD }}
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
       - name: 'Build and push container image'
         uses: docker/build-push-action@f2a1d5e99d037542a71f64918e516c093c6f3fc4
         with:
           context: ./src
           file: ./src/Turnierplan.App/Dockerfile
           push: true
-          tags: '${{ vars.DOCKER_HUB_REPOSITORY }}:latest,${{ vars.DOCKER_HUB_REPOSITORY }}:${{ needs.extract-version.outputs.turnierplan_version }}'
+          tags: 'ghcr.io/turnierplan-net/turnierplan:latest,ghcr.io/turnierplan-net/turnierplan:${{ needs.extract-version.outputs.turnierplan_version }}'
 
   nuget-package:
     name: 'Build NuGet package'

README.md

@@ -12,12 +12,12 @@ This readme describes how to deploy the application using the pre-built containe
 
 ## Deployment
 
-**turnierplan.NET** comes as a pre-built container image which can be deployed with minimal configuration. The image is available on [Docker Hub](https://hub.docker.com/r/eliaspr/turnierplan-net).
+**turnierplan.NET** comes as a pre-built container image which can be deployed with minimal configuration. The image is available on GitHub: [ghcr.io/turnierplan-net/turnierplan](https://github.com/turnierplan-NET/turnierplan.NET/pkgs/container/turnierplan)
 
 In the simplest case, run the container directly using the following command. Make sure to substitute the correct PostgreSQL database connection string:
 
 ```shell
-docker run -p 80:8080 -e ApplicationUrl="http://localhost" -e Database__ConnectionString="" eliaspr/turnierplan-net:latest
+docker run -p 80:8080 -e ApplicationUrl="http://localhost" -e Database__ConnectionString="" ghcr.io/turnierplan-net/turnierplan:latest
 ```
 
 The credentials of the initial admin user are displayed in the container logs.
@@ -69,7 +69,7 @@ services:
     restart: unless-stopped
 
   turnierplan.app:
-    image: eliaspr/turnierplan-net:latest
+    image: ghcr.io/turnierplan-net/turnierplan:latest
     depends_on:
       - turnierplan.database
     environment: