storage.getDocument()
Reads bounded text, JSON, XML, or PDF/DOCX text from Storage. PDF/DOCX
extraction is text-only, capped at 40,000 characters and 100 PDF pages,
with explicit extraction/truncation and possible-OCR metadata. Source input
is limited to 10 MiB; use getFileData for XLSX or record-oriented files.
format: 'text' is the default and supports optional byte ranges.
For text line windows pass startLine/endLine/maxChars; the result contains
line metadata instead of byte offsets. Do not mix line and byte ranges.
format: 'json' returns document from JSON.parse; format: 'xml'
returns an order-preserving XML representation. format: 'auto' selects
JSON/XML from the stored MIME type or file extension.

