Support assistant directs credential account users

Found while investigating Task 12059 (prod, org "Anton Nesterov", support conversation 34, 2026-10-31 20:43 UTC). A tenant pasted the placement refusal "This task cannot be placed: running it in EvilSpace needs a credential account and your organization has none enabled. Ask an operator to add one to your organization." into the Help assistant. The assistant (support_agent) explained "credential" as a Secrets entry (Jira/Slack/GitHub/AWS), said "Your Secrets directory is currently empty", and sent the user to Directory › Secrets. The missing thing was an LLM account on the Accounts page (/accounts, "Add account"), which the user found on their own 20 minutes later. Requirements: - When a user asks about this refusal (or "credential account"), the support assistant points them to Accounts › Add account (an LLM account: subscription login or API key), not Secrets. - The support knowledge base covers what "credential account" means in placement refusals, so retrieval answers it correctly. Out of scope: changing the placement refusal wording or its retry behaviour (the operator decided no change in Task 12059). Done means: - A support-agent test (or KB retrieval test) with the refusal text as the user message expects the answer to name Accounts / Add account and not Secrets. - `./dc check quick` green.

Jarvis now sends "needs a credential account" refusals to Directory › Agents › Add account (guide section + prompt line + Secrets page fix); retrieval test on real docs. Quick gate green; PR #7549 queued in merge lane. Memory: none applied.