ci: use fritzlab/build-image@v1

Replaces inline docker login + metadata + build-push + tag-cleanup
with the shared build-image composite action. Standardizes on
CI_BOT_TOKEN (drops REGISTRY_PASSWORD).

.gitea/workflows/main.yaml

@@ -6,40 +6,12 @@ jobs:
   build:
     runs-on: fritzlab
     steps:
-      - name: Check out repo
-        uses: actions/checkout@v4
+      - uses: actions/checkout@v4
 
-      - name: Log in to Gitea registry
-        uses: docker/login-action@v3
+      - uses: https://code.fritzlab.net/fritzlab/build-image@v1
         with:
-          registry: code.fritzlab.net
-          username: ci-bot
-          password: ${{ secrets.REGISTRY_PASSWORD }}
-
-      - name: Extract Docker metadata
-        id: meta
-        uses: docker/metadata-action@v5
-        with:
-          images: code.fritzlab.net/dns/webhook
-          tags: |
-            type=raw,value=${{ github.run_number }}
-
-      - name: Build and push
-        uses: docker/build-push-action@v6
-        with:
-          context: .
-          push: true
-          provenance: false
-          tags: ${{ steps.meta.outputs.tags }}
-          labels: ${{ steps.meta.outputs.labels }}
-          network: host
-
-      - name: Clean up old image tags
-        run: |
-          tea login add --name ci --url https://code.fritzlab.net --token '${{ secrets.CI_BOT_TOKEN }}' --no-version-check
-          tea api '/packages/dns?type=container' | jq -r '.[] | select(.name=="webhook") | select(.version | test("^[0-9]+$")) | .version' \
-            | sort -n | head -n -3 \
-            | while read tag; do
-                echo "deleting webhook:$tag"
-                tea api -X DELETE "/packages/dns/container/webhook/$tag"
-              done
+          image: code.fritzlab.net/dns/webhook
+          token: ${{ secrets.CI_BOT_TOKEN }}
+          org: dns
+          name: webhook
+          latest: 'false'