The tools field in agent headers now filters which native tools
the agent receives. Empty = all tools (default). Non-empty =
whitelist. Journal agent can list only journal_tail/journal_new/
journal_update. Log shows actual tool names instead of "no tools".
Threaded tools list through call_api_with_tools → sync wrapper →
llm caller.
Co-Authored-By: Proof of Concept <poc@bcachefs.org>