fix(ui): the action key inventory lists disabledReason (#26859)

Part of #26619. This is a main-red hotfix for the spec half (#26786).
The console half is still the PR that closes the card.

Clause-②: no
Metadata-protocol: none
Skills-docs: none (a test-inventory row, no authoring surface)

## 维护者速读

- **改了什么：** `ui/packages/core` 的 `SPEC_ACTION_KEYS` 补上一行
`disabledReason`。
- **为什么改：** #26786 给 `ActionSchema` 加了 `disabledReason`，但 objectui
的动作键清单没跟上，`actionKeys.pin.test.ts` 在 main 上报 missing
`['disabledReason']`，Test UI 红，所有合并 main 的分支都受影响。
- **风险与回滚：** 一行数据，只影响「是否算未知键」的判断。回滚就是 revert 本 PR。
- **需要你做的：** 无，席位落地。

## What changes

- `ui/packages/core/src/actions/actionKeys.ts`: `SPEC_ACTION_KEYS` gains
`'disabledReason'` after `'disabled'`. The list restates every key the
spec's `ActionSchema` declares, and #26786 added that key. An action
that carries it is no longer counted as having an unknown key.
- `.changeset/26619-action-keys-disabled-reason.md`: `@object-ui/core`
patch. (The root `.changeset`, which the changeset gate counts;
`ui/.changeset` is the imported objectui directory.)

## Why

`actionKeys.pin.test.ts` compares `SPEC_ACTION_KEYS` with the keys of
the built `ActionSchema`. Since #26786 merged (`13dc413f`), it fails on
`main` with `missing: ['disabledReason']`. That turns Test UI red on
`main` (`8eef9a8d`) and on every branch that merges `main`. The failure
was reproduced by another card's dev (standing-down comment 6450604330
on PR #26831).

## Verification

- The failure was read on `main` `8eef9a8d`: the pin's `missing` set is
`['disabledReason']` and nothing else.
- The UI workspace dependencies are not installed in this container, so
the pin was not run locally. CI's Test UI on this head is the check.

## Human Minimum

- [x] 1. Schemas start as Zod; `packages/spec` holds no runtime logic.
(`packages/spec` is not touched.)
- [x] 2. Every name I added uses the casing for its kind.
- [x] 3. No formatter ran; `pnpm lint` passes.
- [x] 4. One issue, one branch off an up-to-date `main`, one pull
request.
- [x] 5. A change that publishes carries a changeset, and both
declaration lines are filled in here and in the changeset.
- [x] 6. `packages/spec` touched: its generated artifacts are
regenerated and committed. (Not touched.)
- [x] 7. No hand edits to `content/docs/references/`,
`packages/*/CHANGELOG.md` or `content/docs/releases/`.
- [x] 8. Title, body and comments are in English (apart from the
maintainer quick-read block).
- [x] The *Before Submitting* list in CONTRIBUTING.md is done.

---
_Generated by [Claude
Code](https://claude.ai/code/session_01WGufzfhobWEgUUrjz4rrbh)_

---------

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

Author: os-support-ai

.changeset/26619-action-keys-disabled-reason.md

@@ -0,0 +1,8 @@
+---
+'@object-ui/core': patch
+---
+
+`SPEC_ACTION_KEYS` lists `disabledReason`, the key `@objectstack/spec` added to `ActionSchema` beside `disabled` (objectstack#26786). An action that carries it is no longer counted as having an unknown key, and the inventory pin is green again.
+
+Clause-②: no
+Metadata-protocol: none

ui/packages/core/src/actions/actionKeys.ts

@@ -246,6 +246,7 @@ export const SPEC_ACTION_KEYS = [
   // key, which is the only thing the inventory is consulted for.
   'description',
   'disabled',
+  'disabledReason',
   'errorMessage',
   // No `execute`: its spec-17 tombstone (`retiredKey()`, objectstack#3855) aged
   // out of `ActionSchema` at objectstack#25767 — the spec now refuses it as an