test(frontend): cover trading order filtering

[cursor]

Motivation

Recent Trading tab search work added pure matcher coverage, but the TradingOrders component still lacked coverage for wiring those matchers into the rendered Active/History lists and the active order-book polling set. A regression there could show hidden orders, hide valid matches, or keep polling order books for rows filtered out of the UI.

Changes

• Added src/frontend/src/tests/lib/components/trading/TradingOrders.svelte.spec.ts.
• Covered active-order filtering by token name and verified order-book polling only includes visible active pairs.
• Covered the active no-results state when a filter hides every order without polling hidden pairs.
• Covered History-tab filtering by the localized status label.

Tests

• npm run format:file --file=src/frontend/src/tests/lib/components/trading/TradingOrders.svelte.spec.ts
• npm run lint -- --max-warnings 0
• npm run check:tests
• npm run check
• npm run test -- --run src/frontend/src/tests/lib/components/trading/TradingOrders.svelte.spec.ts src/frontend/src/tests/lib/components/trading/TradingOrderRow.svelte.spec.ts src/frontend/src/tests/lib/components/trading/TradingAssets.svelte.spec.ts (3 files, 16 tests)

Risky behavior now covered: Trading order search must filter visible Active/History rows consistently and must not poll order books for hidden active orders. These tests materially reduce regression risk because they exercise the component-level store/filter/polling integration that pure matcher tests cannot catch.