Use anonymously pullable CI images

.gitea/workflows/ci.yml

@@ -3,7 +3,7 @@
 # Notes for anyone editing this file:
 #
 # Custom runner image
-#   Every job runs inside `gitea.dcglab.co.uk/steve/ci-runner-go`
+#   Every job runs inside `docker.dcglab.co.uk/public/ci-runner-go:latest`
 #   (recipe: https://gitea.dcglab.co.uk/steve/ci/src/branch/main/images/ci-runner-go).
 #   That image already ships:
 #     * Go on PATH at /usr/local/go/bin (so `actions/setup-go` is
@@ -11,8 +11,8 @@
 #       otherwise re-download Go on every job)
 #     * Node.js + npm (used by docs / e2e workflows)
 #     * Docker CLI, Buildx, Compose v2 (used by docker-build steps)
-#   When bumping the Go floor, push a new ci-runner-go image with
-#   the matching Go version and bump the date pin in IMAGE below.
+#   The runner image is intentionally tracked via `latest`: it is shared CI
+#   infrastructure, and updates should propagate to consuming repositories.
 #
 # Self-hosted runner expectations
 #   Each runner host bind-mounts persistent volumes for
@@ -71,10 +71,7 @@ jobs:
     name: Test (${{ matrix.name }})
     runs-on: ubuntu-latest
     container:
-      image: docker.dcglab.co.uk/ci-runner-go:2026-05-15
-      credentials:
-        username: ${{ secrets.ZOT_USERNAME }}
-        password: ${{ secrets.ZOT_PASSWORD }}
+      image: docker.dcglab.co.uk/public/ci-runner-go:latest
     strategy:
       fail-fast: false
       matrix:
@@ -110,10 +107,7 @@ jobs:
     name: Lint
     runs-on: ubuntu-latest
     container:
-      image: docker.dcglab.co.uk/ci-runner-go:2026-05-15
-      credentials:
-        username: ${{ secrets.ZOT_USERNAME }}
-        password: ${{ secrets.ZOT_PASSWORD }}
+      image: docker.dcglab.co.uk/public/ci-runner-go:latest
     steps:
       - uses: actions/checkout@v4
       - uses: golangci/golangci-lint-action@v7
@@ -130,10 +124,7 @@ jobs:
     name: Build (${{ matrix.goos }}/${{ matrix.goarch }})
     runs-on: ubuntu-latest
     container:
-      image: docker.dcglab.co.uk/ci-runner-go:2026-05-15
-      credentials:
-        username: ${{ secrets.ZOT_USERNAME }}
-        password: ${{ secrets.ZOT_PASSWORD }}
+      image: docker.dcglab.co.uk/public/ci-runner-go:latest
     strategy:
       fail-fast: false
       matrix: