Refuse incomplete GraphQL envelopes in survey issue projections #470

🤖 Generated by the Agentic Engineer

Problem

The shipped dependency projection ignores GraphQL errors, while census and association projections accept explicit errors:null. Plausible zero values can therefore clear selection over an incomplete response.

Reproduced offline against freshly fetched main with a valid control. Inspected guidance and repositories were not executed, and no inference or provider test was launched.

Acceptance criteria

All three executable projections accept only object envelopes with absent errors or exactly []; refuse null/scalar/nonempty errors and nonobjects as QUERY-UNKNOWN. Exercise the actual shipped filters with partial-response controls. Size: S.

Part of #51. Related roadmap: #38.