ci: probe key format deeper

.github/workflows/probe-key.yml

@@ -1,4 +1,4 @@
-name: Probe SSH Key Secret
+name: Probe SSH Key Secret v2
 
 on:
   workflow_dispatch:
@@ -7,12 +7,17 @@ jobs:
   probe:
     runs-on: ubuntu-latest
     steps:
-      - name: Decode and hash
+      - name: Decode and inspect
         env:
           SSH_KEY: ${{ secrets.SSH_PRIVATE_KEY }}
         run: |
           echo "$SSH_KEY" | base64 -d > /tmp/k
-          echo "key lines: $(wc -l < /tmp/k)"
           echo "key bytes: $(wc -c < /tmp/k)"
-          echo "sha256(b64): $(echo "$SSH_KEY" | tr -d '\n' | sha256sum | cut -d' ' -f1)"
-          ssh-keygen -y -f /tmp/k >/dev/null 2>&1 && echo "KEYGEN_OK" || echo "KEYGEN_FAIL"
+          echo "first line: $(head -1 /tmp/k)"
+          echo "last line: $(tail -1 /tmp/k)"
+          echo "--- xxd head ---"
+          head -c 60 /tmp/k | xxd | head -3
+          echo "--- ssh-keygen verbose ---"
+          ssh-keygen -y -f /tmp/k; echo "keygen_exit=$?"
+          echo "--- openssl check? ---"
+          base64 --version | head -1