Pin check/renovate back to brick-build now that its image has Node

The runner's label-to-image mapping got repointed at Gitea's own
official runner image (docker.gitea.com/runner-images:ubuntu-latest,
has Node out of the box) — the earlier opensuse/leap:16.0 mapping for
brick-build specifically was what broke check/renovate on 2026-09-12,
not brick-build the label itself. Back to pinning both to this
machine specifically instead of whichever runner answers to the
shared ubuntu-latest label.

.gitea/workflows/ci.yml

@@ -6,15 +6,14 @@ on:
 
 jobs:
   check:
-    # Not brick-build: that label's job container (opensuse/leap:16.0) has
-    # no Node.js, and every step below (checkout, setup-ruby, setup-node)
-    # is a JS-based Action that needs it to even start — see the run that
-    # failed immediately on 2026-09-12. ubuntu-latest is shared with
-    # "Gitea Runner on Cube" too (not pinned to this machine specifically),
-    # but that's fine here: only deploy (runs-on: brick-host, a unique
-    # label held by just the native runner on brick) actually needs to
-    # land on a specific box.
-    runs-on: ubuntu-latest
+    # brick-build's job container now points at Gitea's own official
+    # runner image (docker.gitea.com/runner-images:ubuntu-latest, has
+    # Node out of the box) — the earlier opensuse/leap:16.0 image that
+    # failed here on 2026-09-12 (no Node, every step below is a JS-based
+    # Action) got repointed. Pinned to brick specifically again, rather
+    # than the shared ubuntu-latest label "Gitea Runner on Cube" also
+    # answers to.
+    runs-on: brick-build
     steps:
       - uses: actions/checkout@v4