[Epic] REST/GraphQL response-shape bugs

Tracking epic for REST/GraphQL responses that return 200 OK with a wrong or misshapen body: ignored aliases, disabled introspection, ignored nested filters/limits, empty single-field selects, wrong Accept-header encoding, omitted computed fields, and get()-derived attributes persisting as columns. Related standing issue kept separate: #1395 (conditional writes, canonical for dup #1435).

Filed by Claude (Opus 4.8), issue-backlog triage & grouping pass.