Get Document Placement

Owner-facing field positions + page geometry for a sent envelope.

Same JSON shape GET /api/documents/drafts/{id} returns, so the document details overlay can reuse the editor's wire<->crop conversion (frontend draftService.wireFieldToEditorField) instead of inventing a third coordinate contract. JWT/org-scoped like /content -- this is a dashboard internal, not the API-key GET /api/v1/documents/{id}/fields (submitted values). Missing tags are an empty parsed_fields list, not a 404: the owner still needs to see that nothing was placed. A missing source PDF is also not a 404: stored parsed_fields still return so a completed visual-placement envelope does not look like a tag-less upload (AZL-178).