Fix Linux CI typecheck failure in agent-panel.test.tsx

[Copilot]

Build (linux) was failing during npm run typecheck with TS2322 in tests/ui/agent-panel.test.tsx. The test helper used a mock-specific function type for onHide that was wider than the AgentPanel prop contract.

• Root cause

  • renderPanel typed onHide as ReturnType<typeof vi.fn>, which is not assignable to (() => void) | undefined expected by AgentPanel.

• Change

  • Narrowed onHide typing in the test helper (both override input and helper return type) to match the component prop:
    • onHide?: () => void

• Why this resolves CI

  • Aligns the test helper signature with AgentPanelProps, removing the type incompatibility that breaks typecheck:test on Linux CI.

// before
onHide?: ReturnType<typeof vi.fn>

// after
onHide?: () => void