ci: stop using FORGEJO_* secret names

Forgejo reserves names starting with FORGEJO_, and since runner v13
secrets.FORGEJO_TOKEN, _USER and _REGISTRY no longer reach the job as
the values set on the repository: Kaniko logged in with the wrong
credentials and every image push failed with UNAUTHORIZED.

The registry host and user are not secret (they are in every image
name), so write them in the workflow; the token comes from FJ_TOKEN,
as in datacenterbingo.

Assisted-by: Claude:opus-5-5

.forgejo/workflows/deploy.yaml

@@ -42,17 +42,17 @@ jobs:
         run: |
           # Tags
           SHORT_SHA=${GITHUB_SHA::8}
-          IMAGE_BASE=${{ secrets.FORGEJO_REGISTRY }}/${{ secrets.FORGEJO_USER }}/blog
+          IMAGE_BASE=git.czsk.it/asxpi/blog
           IMAGE_TAG=${IMAGE_BASE}:${SHORT_SHA}
           IMAGE_LATEST=${IMAGE_BASE}:latest
 
           # Auth Conf
           mkdir -p /kaniko/.docker
-          echo "{\"auths\":{\"${{ secrets.FORGEJO_REGISTRY }}\":{\"auth\":\"$(echo -n ${{ secrets.FORGEJO_USER }}:${{ secrets.FORGEJO_TOKEN }} | base64)\"}}}" > /kaniko/.docker/config.json
+          echo "{\"auths\":{\"git.czsk.it\":{\"auth\":\"$(echo -n asxpi:${{ secrets.FJ_TOKEN }} | base64)\"}}}" > /kaniko/.docker/config.json
 
           # Build & push
           /kaniko/executor \
-            --context=git://${{ secrets.FORGEJO_REGISTRY }}/${{ github.repository }}.git \
+            --context=git://git.czsk.it/${{ github.repository }}.git \
             --git=branch=${{ github.ref_name }} \
             --destination=$IMAGE_TAG \
             --destination=$IMAGE_LATEST