ci: adapt workflows for Gitea migration

Change runner from runners-farhoodlabs to ubuntu-latest across all fork
workflows. Update container registry from ghcr.io to git.farh.net and
authenticate with REGISTRY_TOKEN. Migrate update-infra API calls from
GitHub to Gitea. Disable refresh-lockfile.yml (requires GitHub gh CLI).
Update CLAUDE.md references.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

.github/workflows/build-prod.yml

@@ -11,33 +11,27 @@ permissions:
 
 jobs:
   build:
-    runs-on: runners-farhoodlabs
+    runs-on: ubuntu-latest
     timeout-minutes: 30
     steps:
       - name: Checkout
         uses: actions/checkout@v4
 
-      - name: Login to Docker Hub
-        uses: docker/login-action@v3
-        with:
-          username: ${{ secrets.DOCKERHUB_USERNAME }}
-          password: ${{ secrets.DOCKERHUB_TOKEN }}
-
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v3
 
-      - name: Login to GHCR
+      - name: Login to Gitea Registry
         uses: docker/login-action@v3
         with:
-          registry: ghcr.io
-          username: ${{ github.actor }}
-          password: ${{ secrets.GITHUB_TOKEN }}
+          registry: git.farh.net
+          username: ${{ gitea.repository_owner }}
+          password: ${{ secrets.REGISTRY_TOKEN }}
 
       - name: Docker meta
         id: meta
         uses: docker/metadata-action@v5
         with:
-          images: ghcr.io/farhoodlabs/paperclip
+          images: git.farh.net/farhoodlabs/paperclip
           tags: |
             type=raw,value=latest
             type=sha,prefix=