fix: AppHeader usa <Link> para navegación SPA (no full reload); mock en tests de ReportPage

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/features/report/components.test.tsx

@@ -9,6 +9,8 @@ import React from 'react'
 
 // ─── Mocks de dependencias del browser ───────────────────────────────────────
 
+vi.mock('@/components/AppHeader', () => ({ AppHeader: () => null }))
+
 vi.mock('bpmn-js/lib/Viewer', () => ({
   default: class MockViewer {
     importXML = vi.fn().mockResolvedValue({ warnings: [] })