probe: stop filtering away the RUN output

The probe kept succeeding while its results vanished: the grep -vE plus tail -40
dropped the buildkit progress lines that carry the actual curl output. Keep the
full log, then print only the RUN lines with their #N prefix stripped.

.github/workflows/probe-buildkitd.yml

@@ -60,5 +60,7 @@ jobs:
             --frontend dockerfile.v0 \
             --local context="$work" \
             --local dockerfile="$work" \
-            --opt platform=linux/amd64 2>&1 | grep -vE "^#[0-9]+ (sha256|extracting|resolve|DONE|CACHED)" | tail -40
+            --opt platform=linux/amd64 2>&1 | tee /tmp/probe.log | tail -80
+          echo "=== PROBE RESULTS ==="
+          grep -E "^#[0-9]+ [0-9.]+ " /tmp/probe.log | sed -E "s/^#[0-9]+ [0-9.]+ //" || echo "(no RUN output captured)"
           echo "probe finished (results above, from buildkitd's network position)"