Revert "remove artifact upload step from LLM security scan workflow"

This reverts commit d414322.

Author: 0xNeshi

.github/workflows/llm-security-scan.yml

@@ -161,3 +161,11 @@ jobs:
           else
             echo "✅ SCAN PASSED — No vulnerabilities detected."
           fi
+
+      - name: Upload scan output
+        if: always()
+        uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
+        with:
+          name: codex-llm-security-scan-output
+          path: /tmp/scan_output.json
+          retention-days: 30