Why: system.intent ParamsSchema requires top-level text, but
SubmitAction only nested values under data, so button intent always
rejected missing text during prod acceptance.
Evidence: go test ./internal/surfacesvc/ -run TestSubmitActionFlattensDataIntoParams
Impact: B-class intent and other schema-required params work via actions;
submit still receives nested data.
Refs: GenUI prod deploy acceptance; fix track
Co-authored-by: Cursor <cursoragent@cursor.com>