docs(query): stop enumerating a false closed set for the aggregate option keys (#20813)

Fixes #20792

Clause-②: no

Two hand-written docs sentences presented the aggregate option set as a
closed three-key list. The list is false on both paths. This PR keeps
each sentence's true point and drops the enumeration; no key list is
pasted into prose (the generated reference owns it).

## Changes

1. `content/docs/protocol/objectql/query-syntax.mdx` (Analytics: Revenue
by Month)
- Before: "`engine.aggregate()` accepts only `where` / `groupBy` /
`aggregations` (plus a `timezone` for bucketing): there is no `orderBy`
or `limit` on this path, so sort the returned rows yourself."
- After: "`engine.aggregate()` takes a closed option set with no
`orderBy` or `limit` (the full list is under `EngineAggregateOptions` in
the Data Engine reference), so sort the returned rows yourself. It does
carry a `timezone` for bucketing."
2. `content/docs/data-modeling/queries.mdx` (UTC bucketing callout)
- Before: "the `POST /api/v1/data/:object/query` route forwards only
`where` / `groupBy` / `aggregations`, so a query sent over REST always
buckets on UTC calendar boundaries."
- After: "the `POST /api/v1/data/:object/query` route does not forward
`timezone` to the engine, so a query sent over REST always buckets on
UTC calendar boundaries."

3. `content/docs/kernel/contracts/data-engine.mdx` (###
EngineAggregateOptions, added in a second commit 7837c5c)
- Before: an interface literal listing four of the eight keys, with
groupBy typed as a string array.
- After: a one-line pointer to the generated reference,
`/docs/references/data/data-engine#engineaggregateoptions`; the
`AggregationNode` interface and the `distinct` removal note are kept.

## Code anchors (origin/main at 96e7244)

- `packages/objectql/src/engine.ts:562-565`:
`ENGINE_AGGREGATE_OPTION_KEYS` = context, where, groupBy, aggregations,
having, timezone, search, searchFields. Enforced at `:16277`
(`rejectUnknownEngineOptions`). No orderBy / limit, so the kept point
holds.
- `packages/metadata-protocol/src/protocol.ts:11324-11343`: the
engine.aggregate call inside `findData` forwards where, groupBy,
aggregations, having, search, searchFields, context. `timezone` is not
in the bag, and no `timezone` read exists in `findData` (`:10937` to the
call), so REST buckets on UTC.
- `packages/rest/src/rest-server.ts:8808,8849`: `POST
/data/:object/query` calls `p.findData(...)`, confirming the route
reaches that path.
- Generated reference already lists all eight keys:
`content/docs/references/data/data-engine.mdx:891-906`.

## Census (hand-written `content/docs/**`, excluding references/ and
releases/)

Prose patterns: "only `where`", "accepts only", "forwards only",
"groupBy` / `aggregations`", aggregate()-with-only/accepts/forwards,
"drops having/search/timezone".
Interface and type-literal patterns (added after review):
`EngineAggregateOptions`, `AggregateOptions`, `groupBy?:`,
`aggregations?:`, aggregate-signature blocks.
Hits: the three fixed above (`query-syntax.mdx` sentence, `queries.mdx`
sentence, `kernel/contracts/data-engine.mdx` interface literal). Checked
and left: `kernel/contracts/data-engine.mdx:28,39` (an import and the
`aggregate(...)` signature, which name the type and copy no keys),
`:573` (deprecated schema names), `query-syntax.mdx:74-75` (the QueryAST
literal for find, not the aggregate option set), `query-syntax.mdx:85`,
`:1434`, `api/error-catalog.mdx:301`, `api/data-api.mdx:194`. No further
enumeration.

## Acceptance notes

- Stale comment on `ENGINE_DRIVER_PASSTHROUGH_KEYS` deliberately left
out of this PR, as ruled.
- No changeset: docs-only, content/docs is not a published surface.

## Verification

Gate list from `node scripts/pm/dispatch-gates.mjs --commands` (40
families), each run at head 7837c5c with exit 0 (after building
`@objectstack/lint...`, `@objectstack/spec` and
`@objectstack/client-react...` for the gates that read built output);
`--ran` reconciliation: 40 derived, 40 run, 0 NOT-MEASURED, 0 UNRUN.

---
🤖 Generated with [Claude Code](https://claude.com/claude-code)

https://claude.ai/code/session_01VDtqoecgES7ScQYGbFVDRv

---------

Co-authored-by: Claude <noreply@anthropic.com>

Author: objectstack-fleet[bot]

content/docs/data-modeling/queries.mdx

@@ -669,8 +669,8 @@ transparent to the query — you get the same buckets either way.
 <Callout type="warn">
 Buckets are computed in **UTC**. A non-UTC reference timezone is only reachable through
 `ObjectQL.aggregate(object, { …, timezone })`; the `POST /api/v1/data/:object/query`
-route forwards only `where` / `groupBy` / `aggregations`, so a query sent over REST
-always buckets on UTC calendar boundaries.
+route does not forward `timezone` to the engine, so a query sent over REST always
+buckets on UTC calendar boundaries.
 
 The optional `alias` on a structured `groupBy` node is honoured only on the in-memory
 path. The SQL driver ignores it and always projects the bucket under the **field name**,

content/docs/kernel/contracts/data-engine.mdx

@@ -466,14 +466,11 @@ const result = await engine.aggregate('task', {
 
 ### EngineAggregateOptions
 
-```typescript
-interface EngineAggregateOptions {
-  where?: FilterCondition;                 // Pre-aggregation filter (WHERE)
-  groupBy?: string[];                      // GROUP BY fields
-  aggregations?: AggregationNode[];        // Aggregation definitions
-  context?: ExecutionContext;
-}
+The option keys are listed in the generated
+[`EngineAggregateOptions` reference](/docs/references/data/data-engine#engineaggregateoptions).
+`aggregations` takes `AggregationNode` entries:
 
+```typescript
 interface AggregationNode {
   function: 'count' | 'sum' | 'avg' | 'min' | 'max' | 'count_distinct';
   field?: string;           // Field to aggregate (optional for COUNT(*))

content/docs/protocol/objectql/query-syntax.mdx

@@ -1334,9 +1334,10 @@ const products = await engine.find('product', {
 ### Analytics: Revenue by Month
 
 `month` is not a column — bucket the `created_at` instant with `dateGranularity`. Note
-that `engine.aggregate()` accepts only `where` / `groupBy` / `aggregations` (plus a
-`timezone` for bucketing): there is no `orderBy` or `limit` on this path, so sort the
-returned rows yourself.
+that `engine.aggregate()` takes a closed option set with no `orderBy` or `limit` (the
+full list is under `EngineAggregateOptions` in the
+[Data Engine reference](/docs/references/data/data-engine)), so sort the returned rows
+yourself. It does carry a `timezone` for bucketing.
 
 ```typescript
 const monthlyRevenue = await engine.aggregate('order', {