ci(grid-rs): surface docker daemon diagnostics on wait-step failure

Mirrors the verbose wait-for-docker block from build.yaml so future "failed
to connect to docker" failures print socket permissions, docker-related
env vars, and full `docker info` output instead of a single unhelpful line.

.forgejo/workflows/build-grid-rs.yaml

@@ -49,14 +49,31 @@ jobs:
 
       - name: Wait for Docker daemon
         run: |
+          # act_runner mounts the host docker socket into the job, but
+          # the daemon side sometimes takes a moment to answer. Poll
+          # `docker info` until it responds so the login/build steps
+          # below don't race the socket and fail with "unable to
+          # connect to docker". Mirrors the diagnostics in build.yaml
+          # so failures surface *why* the socket is unreachable.
+          sock="${DOCKER_HOST:-unix:///var/run/docker.sock}"
+          echo "Using DOCKER_HOST=${sock}"
+
           for i in $(seq 1 30); do
             if docker info >/dev/null 2>&1; then
               echo "Docker daemon reachable after ${i}s"
               exit 0
             fi
+            echo "Waiting for Docker daemon... ($i/30)"
             sleep 1
           done
-          echo "Docker daemon never became reachable" >&2
+
+          echo "Docker daemon never became reachable — diagnostics:" >&2
+          echo "--- ls -l /var/run/docker.sock ---" >&2
+          ls -l /var/run/docker.sock 2>&1 || true
+          echo "--- env | grep -i docker ---" >&2
+          env | grep -i docker 2>&1 || true
+          echo "--- docker info (verbose) ---" >&2
+          docker info 2>&1 || true
           exit 1
 
       - name: Generate image tag