docs(changeset): leave the structured-JSON groupBy entry as it landed; this entry names the two shapes it narrows (#20808)

Claude-Session: https://claude.ai/code/session_01DEvba2nBuD4tWzfq8r8NFY
Co-authored-by: Claude <noreply@anthropic.com>

Author: claude

.changeset/20783-groupby-structured-json-refused.md

@@ -16,4 +16,4 @@ Clause-②: no (narrowing)
 
 **Who is affected.** A caller of `engine.aggregate` or of the REST query door that grouped by such a field on the in-memory driver or on SQLite and read the merged or per-serialization groups as real ones. On PostgreSQL the same query was already a 500. The analytics service's aggregate path (a cube query the native-SQL strategy declines, such as a time dimension with a granularity, or any cube query on the in-memory driver) reaches the engine and answers this refusal too.
 
-**Unchanged by this entry.** A `groupBy` on a scalar-stored type (`text`, `number`, a single-value file field), a structured-JSON field as an AGGREGATED column (`count`, `min`, `max`), and an undeclared name, which the REST door answers `INVALID_FIELD` as unknown before the engine is reached. A `groupBy` on a multi-value field and a `count_distinct` over a structured-JSON field are refused too, by the multi-value / JSON-stored entry of this same release.
+**Unchanged.** A `groupBy` on any other type (`text`, `number`, a `multiple: true` select, a file field), a structured-JSON field as an AGGREGATED column (`count`, `count_distinct`, `min`, `max`), and an undeclared name, which the REST door answers `INVALID_FIELD` as unknown before the engine is reached.

.changeset/20808-json-stored-group-distinct-refused.md

@@ -26,7 +26,7 @@ Clause-②: no (narrowing)
 
 **Who is affected.** A caller that grouped by a multi-value field, or counted a JSON-stored field distinct, on the in-memory driver or on SQLite and read the answer as a real one; on PostgreSQL both were already a 500. A dataset whose measure pairs `count_distinct` with a JSON-stored field is refused by the lint rule and the compile leg.
 
-**Unchanged.** A `groupBy` or `count_distinct` on a scalar-stored field, a single-value `select` or `lookup` included; `count` over any field; the `having`, filter and sort positions; and an undeclared name, which the REST door answers `INVALID_FIELD` as unknown before the engine is reached.
+**Unchanged.** (Two shapes the structured-JSON `groupBy` entry of this same release lists as unchanged are narrowed here: a `multiple: true` select as a group key, and `count_distinct` over a structured-JSON field. This entry is the later word on both.) A `groupBy` or `count_distinct` on a scalar-stored field, a single-value `select` or `lookup` included; `count` over any field; the `having`, filter and sort positions; and an undeclared name, which the REST door answers `INVALID_FIELD` as unknown before the engine is reached.
 
 `@objectstack/lint`: the dataset-measure refusal's hint no longer says `count_distinct` accepts every type.