3f596f81 — heading-tree structure of an ingested .docx for the Documents panel. Calls the stateless docs_intel.document_outline (paragraph_count + heading_count + an ordered heading list). Returns {"error": ...} on a missing/unreadable/non-docx file rather than a 500 so the panel renders the failure inline.

NOTE: path is resolved on the SERVER — this works for self-hosted / tunnel setups where the server can see the file; a hosted server has no access to the user's local filesystem, so it returns an error the panel surfaces.