ci: temporary probe workflow to diagnose repo-wide startup_failure

Author: hyperpolymath

.github/workflows/zz-probe.yml

@@ -0,0 +1,14 @@
+# SPDX-License-Identifier: MPL-2.0
+name: ZZ Probe
+on: push
+permissions:
+  contents: read
+jobs:
+  probe:
+    runs-on: ubuntu-latest
+    timeout-minutes: 5
+    steps:
+      - name: Checkout
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - name: Say hello
+        run: echo "probe ok"