feat(TWO-25326): unify Luma order-intent checking UI with the other plugins

[dgjlindsay]

What

Unifies the order-intent checking UI on Luma with the other three plugins (TWO-25326).

Before, Luma showed a wordless spinner while the check ran, then stated an approval in the module's brand blue, a decline in a warm red, and an error only as a checkout toast. Each plugin looked different.

Now:

1. During the check — the same spokes figure (images/loader.gif, already shipped) with the sentence "Checking availability" beside it. Translated in every locale this module ships (nb_NO, nl_NL, sv_SE); the retired Checking company row is removed from all of them. The visible text names the role="status" region, so the figure carries aria-hidden and the old aria-label is gone.
2. The result — all three outcomes (approved, declined, errored) render in the one bordered box, with the semantic palette: success green for an approval, danger red for a decline, the box's neutral colours for an error. The intent message is the only thing inside it — no title above it. The error case previously had no persistent surface at all: it went to the checkout message region, which is cleared on the next checkout update.
3. Stale verdict — the previous outcome is cleared as a new check starts, not when its answer arrives.

Why (3) was actually broken

The company-change subscriptions looked like they covered it, and they do not. They fire when a company observable changes; a check can start with those observables already holding the same values — a re-render re-applying the captured company, or a repeat pick of the company already in the field — and knockout notifies nobody. In exactly those cases the previous company's approval stayed on screen for the whole of the next request, under a spinner checking something else.

Tests

npm run test:js — 29 suites, 383 tests, green. New/changed coverage:

• the in-flight row: spokes GIF retained, text beside it, aria-label gone, and every shipped locale CSV carries a non-stub translation of the new string (asserted against the CSVs on disk, so a locale added later is covered without editing the spec)
• all three outcomes share the container class, each box holds only its text:-bound message and no heading
• the semantic palette values
• error goes to the box and not the toast; a brand suppressing the verdict does not silence it; SCHEMA_ERROR's per-field errors still go to the fields
• the verdict is cleared during a new check, asserted with an observable that has real knockout's equality semantics — the AMD harness's double notifies on every write, which would have made that assertion vacuous

Mutation-checked: removing the clear-at-start call fails exactly one spec.

Notes

The palette values match the reference box style being normalised on PrestaShop in the same batch, so a buyer meeting two of the four plugins reads the same colour for the same outcome. No brand overlay styles these classes, so nothing downstream is silently overridden.

[dgjlindsay]

Adversarial self-review — round 1, clean

Reviewed the full diff against origin/staging...HEAD for knockout binding correctness, CSS specificity/overlay-override breakage, buyer-facing paths where a message could now be swallowed, observables read before they exist, vacuous tests, i18n CSV format, and missed call sites of the old behaviour.

No findings. Specifically checked and confirmed:

• i18n: binding syntax matches the template's existing usage; the ko if: virtual binding still wraps the new row
• all three locale CSVs carry the new string, and the retired Checking company row is gone from all of them
• the indicator selectors stay single flat classes, per the rule documented on .two-company-search__spinner — brand overlays can still override at equal specificity
• every new observable read is existence-guarded, and the error path falls back to the toast if its observable is not wired yet, so no error can be swallowed by the change of surface
• SCHEMA_ERROR's per-field errors still go to the fields, not the box
• no other call site depended on the old wordless spinner element or the old notice-clearing statements

The clear-at-start behaviour is mutation-checked: removing the call fails exactly one spec, so that assertion is not vacuous.

npm run test:js: 29 suites, 383 tests, green.

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_{Review performed by Claude.}