Add credential tester agent matching Splunk agent credential names

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: bmbouter

.alcove/agents/credential-tester.yml

@@ -0,0 +1,12 @@
+name: Credential Tester
+description: |
+  Tests that all credentials required by the Splunk agent are injected
+  correctly. Uses debug-env to show environment variables with masking.
+executable:
+  url: file:///usr/local/bin/debug-env
+timeout: 60
+direct_outbound: true
+credentials:
+  SPLUNK_TOKEN: splunk
+  JIRA_API_TOKEN: jira
+  VERTEX_SA_JSON: google-vertex