Item helpers and client validation for the personality and Docstion sections — items.ts and collabItems.ts edit exactly one identity and hand every other item back as the same object (CP-D14 extended to keys and kinds), validate.ts mirrors CharterItems' PERSONALITY and DocsTION rules without the lint, validateItems runs both whether or not the sections are shown, and the editor words GROUP_INCONSISTENT, UNKNOWN_VALUE and FIELD_NOT_ALLOWED (KamoCollab CP09 Task 9)