docs(skills): object-level composite/repeater are untyped JSON — a typed list is a child object (#25741)

Refs #25681

Clause-②: no
Metadata-protocol: none
Ruling-ref: 6386744473

The governed half of ruling 6386744473 (batch #12 item 4, letter b):
object-level `composite` / `repeater` are untyped JSON, and a typed list
is a child object. The code and docs half is the companion PR on
`claude/issue-25681-repeater-untyped-json`. It is split off because
`skills/**` is a Tier H governed surface and never rides a code PR.

## What changed

- `skills/objectstack-data/rules/field-types.md`, the Embedded table.
The `composite` row said "Single embedded sub-object with declared
sub-fields". An object field has no member that declares sub-fields:
`fields`, `subFields` and `columns` are refused on the field (true on
`main` today, measured with `FieldSchema.safeParse`). Both rows now say
the type is untyped JSON. The `repeater` row names the route: a child
object with a `master_detail` field, and `inlineEdit: 'grid'` to edit it
inline.
- `.changeset/25681-skills-repeater-untyped.md`: `@objectstack/skills`
patch. Its `dist` ships the skill files, the same as the precedent
`061cc94d`.

## Size readings

| reading | before | after |
|---|---|---|
| `skills/objectstack-data/rules/field-types.md` | 322 lines | 322 lines
|
| whole catalog (sum of every `skills/*/SKILL.md`) | 4389 lines | 4389
lines |

Two cells rewritten, zero lines added: no expansion.

## Verification (head `14a58a3a`)

`node scripts/pm/dispatch-gates.mjs --repo objectstack-ai/objectstack
--ran …` → `✓ 44 derived famil(ies) accounted for — 39 run, 5
NOT-MEASURED (5 DERIVED from a recorded exit 3)`. All 39 that ran exited
0, `check-skills-token-ratchet.mjs` and its `--self-test` among them.
The 5 NOT MEASURED are prerequisite refusals in an unbuilt worktree
(`check:doc-formula-expressions`, `check:dts-closure`,
`check:dual-build-cjs-loads`, `check:lean-entry-closure`,
`check:sourcemap-no-sources-content`); CI builds and runs them.

## 维护者速读(草稿)

- **改了什么**:对外发布的技能包里，`objectstack-data` 的字段类型表有两行改了措辞：`composite` /
`repeater` 是无类型
JSON，对象字段不能声明子字段；要带列的列表请建子对象（`master_detail`，`inlineEdit: 'grid'`
在父表单内联编辑）。另附一条 `@objectstack/skills` patch changeset。
- **为什么改**:旧文写着「declared sub-fields」，可协议里根本没有声明子字段的成员，AI
照着技能包写就会写出被拒收的字段。这是裁决 6386744473（25681 b）的技能包一半；代码与文档一半在配套 PR。
- **风险与代价(含回滚)**:纯文档，行数不变（322 → 322；技能包合计 4389 → 4389），不改任何键、值或行为。回滚就是
revert 这一个提交。
- **席位意见**:
- **你要做的**:`skills/**` 属 Tier H。复核通过、CI 全绿后请您批准合并。

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

https://claude.ai/code/session_01T2U7eGg8aRTpJ8kKXxDiog

---
_Generated by [Claude
Code](https://claude.ai/code/session_01T2U7eGg8aRTpJ8kKXxDiog)_

---------

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

Author: objectstack-fleet[bot]

.changeset/25681-skills-repeater-untyped.md

@@ -0,0 +1,12 @@
+---
+'@objectstack/skills': patch
+---
+
+docs(skills): object-level `composite` / `repeater` are untyped JSON — a typed list is a child object
+
+Clause-②: no
+Metadata-protocol: none
+
+The `objectstack-data` field-types table said a `composite` carries "declared sub-fields". An object field has no member that declares them: `fields`, `subFields` and `columns` are refused on the field. The two rows now say the types are untyped JSON and that a list needing typed columns is a child object with a `master_detail` field (`inlineEdit: 'grid'` edits it inline on the parent's form).
+
+What to do: nothing. No key, value or behaviour changes.

skills/objectstack-data/rules/field-types.md

@@ -113,8 +113,8 @@ Stored as JSON on the parent row — no separate table / FK:
 
 | Type | When to Use |
 |:-----|:------------|
-| `composite` | Single embedded sub-object with declared sub-fields |
-| `repeater` | Repeating embedded sub-object **array** |
+| `composite` | Single embedded JSON object, **untyped** — a field declares no sub-fields (`fields` / `subFields` are refused) |
+| `repeater` | Embedded JSON **array**, **untyped** — no sub-fields or `columns`; a typed list is a child object (`master_detail`, `inlineEdit: 'grid'`) |
 | `record` | Name-keyed **map** of embedded sub-objects (insertion order = display order; ADR-0007) |
 
 ## Calculated