fix(ci): target the golang runner, generic docker runner retired

.gitea/workflows/build.yaml

@@ -15,7 +15,11 @@ env:
 jobs:
   build:
     name: Build and push image
-    runs-on: docker
+    # golang, not a retired generic "docker" runner -- this repo is Go, and
+    # every runner now carries its own dind sidecar to build/push that
+    # repo's images. `container.image` below overrides the runner's own
+    # default (golang:1.25-bookworm) with docker:27-cli for this job only.
+    runs-on: golang
     container:
       image: docker:27-cli
       # No `options: --network host` here -- act_runner ignores that per-job

.gitea/workflows/ci.yaml

@@ -12,7 +12,8 @@
 # .forgejo/workflows/ specifically appears unsupported on this instance/version,
 # not workflow detection being off in general.
 #
-# runs-on: docker matches the only label the cluster runner declares.
+# runs-on: golang -- the generic "docker" runner was retired in favor of
+# per-language runners (golang/node/rust), each with its own dind sidecar.
 name: CI
 
 on:
@@ -24,7 +25,7 @@ on:
 jobs:
   verify:
     name: Test, vet, build
-    runs-on: docker
+    runs-on: golang
     container:
       image: golang:1.25-bookworm
     steps: