test(frontend): cover borrow opportunity list

[cursor]

Motivation

Recent Borrow-page work added a new provider registry -> derived data -> opportunity-card list path. The page-level Borrow spec asserted high-level text, but it did not protect the list wiring, borrow-specific APY framing, action navigation, or the guard that hides providers without derived data. Covering this path reduces regression risk for a business-critical lend/borrow entry point where an empty or mis-framed card list would be user-visible.

Changes

• Added a reusable Liquidium borrow provider fixture in src/frontend/src/tests/mocks/earning-providers.mock.ts.
• Added src/frontend/src/tests/lib/components/borrow/AllBorrowOpportunityCardList.spec.ts.
• Covered rendering only when provider data is present, Borrow APR badge text/class, action button copy, and goto navigation.

Tests

• npm run prepare
• npm run test -- src/frontend/src/tests/lib/components/borrow/AllBorrowOpportunityCardList.spec.ts
• npm run format:file --file=src/frontend/src/tests/mocks/earning-providers.mock.ts
• npm run format:file --file=src/frontend/src/tests/lib/components/borrow/AllBorrowOpportunityCardList.spec.ts
• npm run lint -- --max-warnings 0
• npm run check
• npm run test (passes; existing unrelated Vitest runtime warnings are still printed)
• npm run check:tests
• npm run lint:lockfile
• npm run format