test(dogfood): the persona matrix hangs its invoice lines off an unpaid invoice (#24832)

Refs #24780
Clause-②: no

**This is row 3 of #24780** (triage pointer `6286191020`): the stale
fixture in `showcase-crud-persona-matrix.dogfood.test.ts`. Row 1 is PR
#24805, which landed as `c56115bf9`. Row 2 belongs to #24749. #24780
remains open: the PM closes it once rows 1 and 3 have both landed.

## What changes

One fixture line in
`packages/qa/dogfood/test/showcase-crud-persona-matrix.dogfood.test.ts`,
in `beforeAll`:

- **Before:** `seed.invoiceId = await firstId('showcase_invoice')`,
which takes whichever invoice a `limit: 1` read returns first.
- **After:** the first invoice whose `status` is not `paid`. That is the
state the showcase's paid-invoice line lock reads (the
`showcase_guard_paid_invoice_line_*` hooks test `header.status ===
'paid'`). It follows the pattern of the `[#18682]` account choice
directly above it, and the new comment explains why.

The lock from PR #24731 is unchanged. This PR changes no case assertion,
no other dogfood file, and nothing under `examples/app-showcase/**` or
`packages/spec/**`.

## Why

- The admin payload control creates a `showcase_invoice_line` under
`seed.invoiceId` and asserts a status below 300. Since PR #24731, the
showcase refuses a line insert under a paid invoice with a 400: "This
invoice is paid, so its lines are locked: a line cannot be added to it."
- `firstId` does not pick the same invoice each time. On `ab9890169` I
measured three boots. The `limit: 1` read returned INV-1012 (sent), then
INV-1008 (sent), then INV-1005 (paid). The ids are random and differ on
every boot. The unlimited read returned insertion order every time, with
INV-1001 first. The seed holds 12 invoices, and 5 of them are paid. So
the control fails on some boots and passes on others.
- CI shows the same pattern. Shard 3/3 on `74f78159af` was red in push
run 39376439272 and green in schedule run 39378039597. On `a43405d596`
it was red in schedule run 39384364728. I also read four `main` runs
from before `576d0f3733`, and shard 3/3 was green in all of them.

## Evidence

Every run used `pnpm --filter @objectstack/dogfood exec vitest run
--maxWorkers=2 FILE` under `os-verify-lock`, after building the closure
with `turbo run build --filter='@objectstack/dogfood^...'`. This file
belongs only to the `isolated` project. The gate runs `turbo run test
--filter=@objectstack/dogfood` with `OS_TEST_SHARD=k/3`.

On an unmodified file, red or green comes down to which invoice the boot
happens to draw. So the red/green comparison uses an uncommitted scratch
copy whose only change forces the parent to a paid invoice (`where: {
status: 'paid' }`):

| tree | parent | result |
|---|---|---|
| `4e0f5f50d` (`576d0f3733^`) | forced paid | `Tests 46 passed (46)`,
VERDICT command-exit 0 |
| `576d0f373` (PR #24731) | forced paid | FAIL: "admin control: the
showcase_invoice_line payload is VALID (...) got {"error":"This invoice
is paid, so its lines are locked: a line cannot be added to
it.","object":"showcase_invoice_line"}: expected 400 to be less than
300", VERDICT command-exit 1 |
| `ab9890169` (`main`, the base) | forced paid | the same FAIL at the
assertion CI cites (`:369`), VERDICT command-exit 1 |
| `8c65e505a` (the fix) | the fix | `Tests 46 passed (46)`, VERDICT
command-exit 0 |
| `0503d47c6` (final head, `main` merged) | the fix | `Tests 46 passed
(46)` on each of two runs |

Only `examples/app-showcase`, a changeset and one docs file differ
between the two bisect trees, and the dogfood suite loads the showcase
from source. So a single built closure served both legs, and the matrix
file is byte-identical across the pair.

**Which lines hang off a seeded invoice.** I ran a probe on `8c65e505a`:
a scratch copy with one extra reporting case, not committed. Only
`showcase_contributor` creates a line. That persona's `showcase_invoice`
row runs first, and its line hangs off its own invoice, whose status is
`draft`. The only line under a seeded invoice is the admin control's, so
fixing this one parent fixes every place in the file with this cause.

No ablation: product behaviour does not change.

## Gates (final head `0503d47c6`)

- `node scripts/pm/dispatch-gates.mjs --commands --repo
objectstack-ai/objectstack` derived 56 commands from 1 changed path. All
56 ran, each with its exit code captured before any pipe. `--ran`: "56
derived famil(ies) accounted for — 56 run, 0 NOT-MEASURED (a DERIVED
zero — all 56 recorded an exit code and none of them is 3)."
- `check:dual-build-cjs-loads` first exited 3 (PREREQUISITE NOT MET: 8
packages had no `dist`). I built those 8 and re-ran it: exit 0, "112
published require entry point(s) across 69 package(s) load".
- `pnpm lint` (`eslint . --no-inline-config`): exit 0, no findings.
- `pnpm --filter @objectstack/dogfood run typecheck`: exit 0. `tsc
--listFilesOnly` lists the edited file.
- `check-nul-bytes: OK (scanned 12537 text file(s) ...; no raw ASCII
control bytes)`.

## Changeset

`skip-changeset`: the diff is one test file in `@objectstack/dogfood`,
which is `private: true` and publishes nothing.

## Acceptance notes

- The file's other seeded parents (`showcase_product`,
`showcase_project`, `showcase_expense_report`, `showcase_team`) still
use `firstId`, so they are also drawn at random on each boot. Today no
rule makes any of those choices refuse a payload, and every pre-lock run
I read was green. If a state rule is added to one of those objects, its
parent should be chosen the same way.

---
_Generated by [Claude
Code](https://claude.ai/code/session_01LmjU2x1faLZ39DVTFyVca6)_

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

Author: objectstack-fleet[bot]

packages/qa/dogfood/test/showcase-crud-persona-matrix.dogfood.test.ts

@@ -324,7 +324,19 @@ describe('showcase: persona × CRUD-cell matrix (#9481)', () => {
     );
     seed.productId = await firstId('showcase_product');
     seed.projectId = await firstId('showcase_project');
-    seed.invoiceId = await firstId('showcase_invoice');
+    // NOT `firstId` either, for the same reason as the account: the showcase
+    // locks a PAID invoice's lines (its `showcase_guard_paid_invoice_line_*`
+    // hooks), so a line can be neither added under one nor removed from one.
+    // `firstId` takes whichever invoice a `limit: 1` read returns, and with
+    // random ids that is a different invoice on every boot — several seeded
+    // invoices are paid, so the admin control below failed on some boots and
+    // not others. Every line this file creates under a seeded invoice hangs
+    // off this one, so the parent is chosen by the state the lock reads.
+    seed.invoiceId = String(
+      (await ql.find('showcase_invoice', {
+        where: { status: { $ne: 'paid' } }, limit: 1, context: SYS,
+      }))?.[0]?.id ?? '',
+    );
     seed.expenseReportId = await firstId('showcase_expense_report');
     seed.teamId = await firstId('showcase_team');
     expect(