Sentinel campaign audit skill

extended .claude/commands/txt-sentinel.md with a new audit [campaign_id] mode. Calls run_sentinel via MCP, auto-fixes unresolved wiki-links by calling resolve_article_reference per [[Name]] and re-triggering the WikiLinkResolver via update_article when the target exists, and surfaces orphans/privacy leaks/stale session articles as a DM judgment list. Reporting format extended with an audit-mode block. Existing infra QA modes (verify/investigate/hunt) unchanged; audit is mode-dispatched on presence of campaign_id.