docs(data-api): state what the analytics query result's fields[] really declares

The callout said each entry carries exactly `name` and `type` "and nothing
else", and that reading `label` / `format` off a query result yields
`undefined`. `AnalyticsResultResponseSchema` declares `label` / `format` /
`currency` / `percentScale` / `builtinAggregate` as optional members and the
`AnalyticsResult` contract mirrors them, so both sentences are false on this
tree. Rewrite the callout in the conditional form the schema supports and keep
the cube-metadata pointer as the declaration surface it is.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Vbw3RPgdtqesx4azk9SbW8

Author: claude

content/docs/api/data-api.mdx

@@ -420,16 +420,23 @@ Filtering uses the canonical Query DSL `where` object (the same MongoDB-style `F
 ```
 
 <Callout type="info">
-**`fields[]` describes columns, not presentation.** Each entry carries exactly `name` and
-`type` — that is the whole descriptor `AnalyticsResultResponseSchema` declares, and every
-strategy answering this endpoint emits those two keys and nothing else.
-
-Display name and number format live one layer up, in the **cube's metric/dimension
-definition** (`MetricSchema.label` / `MetricSchema.format`, `DimensionSchema.label`), and
-are read from cube metadata — `GET /analytics/meta` below reports each measure's and
-dimension's declared label as `title`. Reading `data.fields[i].label` or
-`data.fields[i].format` off a query result yields `undefined`; a client that renders table
-headers or formats amounts reads them from the cube metadata instead.
+**`fields[]` is the resolved presentation surface — read it first.** Each entry carries
+`name` and `type` and, when the producer declares them, `label`, `format`, `currency`,
+`percentScale` and `builtinAggregate`: the optional members
+`AnalyticsResultResponseSchema` declares (`packages/spec/src/api/analytics.zod.ts`),
+mirrored member for member by `IAnalyticsService.query`'s `AnalyticsResult` and bound to
+it at compile time. Optional means a given column may omit them — read them defensively,
+never as guaranteed present.
+
+The **cube's metric/dimension definition** (`MetricSchema.label` / `MetricSchema.format`,
+`DimensionSchema.label`) is the *declaration* surface, not a substitute for this one.
+`GET /analytics/meta` below publishes a deliberately narrow projection of it — `name`,
+`type` and `title` (the definition's `label`) only, with `format` dropped
+([#6442](https://github.com/objectstack-ai/objectstack/issues/6442)). So a client that
+renders table headers or formats amounts takes `label` / `format` / `currency` /
+`percentScale` off the query result's `fields[]`: those are resolved server-side (the
+ADR-0053 currency chain, the percent-scale chain), and `format` is not reachable through
+the metadata endpoint at all.
 </Callout>
 
 ### `GET /analytics/meta`