Use cuerdas blank-name handling directly when normalizing frontend export
payloads. Replace nil or blank export names with the object-id string in
request-simple-export, request-multiple-export, clipboard export, and plugin
direct export payloads so that the backend always receives a valid name. Add
focused frontend tests for nil/blank name normalization and normalized request
params.
AI-assisted-by: nex-n2-pro
040080749b