OUTPUT FORMATS:

MARKDOWN (default, -f markdown):
  ## Documents

  Found 3 results:

  - [Document A](doc-a) (root)
  - [Document B](doc-b) <- [Document A](doc-a)

  Each result shows:
  - Document link
  - (root) indicator if no parents
  - Parent documents with <- notation (where this doc is embedded)

KEYS (-f keys):
  One key per line, suitable for piping:

    doc-a
    doc-b
    doc-c

JSON (-f json):
  Structured output with metadata:

    {"query": "...", "total": 3, "results": [
      {"key": "...", "title": "...", "is_root": true,
       "incoming_refs": 5, "outgoing_refs": 2, "parent_documents": [...]}]}