Playwright ladder-config.spec fails on main: 'Dismiss notification' strict-mode violation #802

The Frontend E2E check "Playwright Chromium" fails on main in frontend/tests-e2e/ladder-config.spec.ts ("ladder editor preserves selections and resets new configs at 1280px"):

locator.click: strict mode violation: getByRole('button', { name: 'Dismiss notification' }) resolved to 2 elements

Evidence:

• Failing main run: https://github.com/LeanerCloud/cloud-commitments-platform/actions/runs/37958856836 (head 6125d2c).
• Reproduced locally on a clean origin/main checkout (0a76043): npx playwright test ladder-config fails 2 of 2, always the 1280px case.
• Also fails on feat(frontend): explicit Archera comparison section #801, which does not touch this file or the ladder page.

Two toast "Dismiss notification" buttons are present when the spec clicks one; the locator needs scoping (or the duplicate toast needs explaining). "Playwright Chromium" is not a required check, so merges are not blocked, but the failure hides real regressions in this suite.