fix(ui): block Enter on a form with several options

[0065paula]

What

Enter inside a field no longer submits a form with two or more setting options; submission comes from the submit button (Tab to it and press Enter, or click it). Single-field forms and widgets that own Enter (comboboxes, array entry editors, textareas) keep their behaviour.

Two prerequisites surfaced while doing this:

• keyboard focus was invisible on every button — Tailwind reads shadow-[var(…)] as a shadow colour, so the focus ring and the push-button/card/menu shadows were never rendered (29 places);
• nothing prevented the same mistake from coming back.

Changes

• foundation/lib/enter-submit.ts + foundation/hooks/use-form-enter-submit-guard.ts, wired into ResourceForm, CreateApiKeyForm, ApiKeyLimitsCard and FunctionDialog. Complexity is counted from the data-form-option markers FormFieldGroup renders, so a single-field form (Workspace) keeps native Enter-to-submit. A composing Enter is left to the input method and only its follow-up submit is refused.
• Focus-visible now follows the design system's button and checkbox spec: 2px outline, 2px offset, stroke-outstanding-base (stroke-serious-base for Danger) on button-like controls; form fields keep the effect-outline-active-focus halo. All 29 ambiguous shadow utilities were switched to [box-shadow:var(…)], or shadow-[shadow:var(…)] where the shadow composes with ring-*.
• tools/check-shadow-utilities.cjs rejects the ambiguous syntax; it runs in the pre-commit hook and from yarn lint:ci, which CI already executes.

Verification

• yarn typecheck, yarn dep-check, yarn knip, biome, both i18n gates and the new shadow check pass.
• New unit tests: field Enter blocked in a two-option form, kept in a single-option form, Enter on the submit button untouched, a widget that already claimed Enter (defaultPrevented), and a composing Enter whose follow-up submit is refused. The only local failures are the pre-existing Timestamp.render.test.tsx timezone cases (they also fail on main outside UTC).
• Browser QA on the mock preview: field Enter does not submit; Tab to Save + Enter submits; ArrowDown + Enter still selects in a combobox; CTA/Ordinary focus shows outline: 2px solid rgb(0,128,255) with outline-offset: 2px and the button shadow restored; input halo unchanged.

Notes

• Deliberately out of scope: auth pages (Enter-to-submit is expected there) and playground chat inputs (Enter sends).

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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[Yuyz0112]

Thanks for the review. Please address the following points:

1. package.json:104: Could this hook configuration follow the same pattern as the other commit hooks, rather than being added to lint? Please clarify the intended convention and keep the configuration consistent.

2. src/domains/api-key/components/ApiKeyLimitsCard.tsx:167 and src/domains/endpoint/components/FunctionDialog.tsx:194: The form-related handling appears to be implemented in several scattered places, which may allow similar issues to recur. Could we consider extracting a shared abstraction for this behavior, or explain why a shared abstraction would not fit here?