Changes to Edit a single memory in place while preserving its ID and usefulness posterior. Modes: 'replace' overwrites entire content; 'exact' performs surgical find-and-replace of oldString→newString (fails if missing or ambiguous)

added the non-success response with the status 403

added the media type application/json for the response with the status 200

added the media type application/json for the response with the status 400

added the media type application/json for the response with the status 404

added the media type application/json for the response with the status 409

endpoint added