Initial scaffold: Researcher Endorsement frontend

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

.github/agents/vitest-navigator.md

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+---
+name: "Vitest Navigator"
+description: "Generates Vitest + Testing Library unit test templates for Atomic components."
+triggers:
+  - "generate tests"
+  - "create vitest test for PaperCard"
+  - "unit test EndorsementBadge"
+---
+
+# Vitest Navigator
+
+Purpose
+- Automatically produce unit test skeletons for Atoms and Molecules (render + interaction assertions).
+
+Example prompts
+- "generate a vitest test for PaperCard"
+- "create tests to assert the Endorsement button updates the store"
+
+Output
+- Test files under `src/components/{atoms|molecules}/__tests__/{Component}.test.tsx` using `@testing-library/react` and `vitest`.
+
+Example test (PaperCard)
+```ts
+import React from 'react'
+import { render, screen, fireEvent } from '@testing-library/react'
+import { describe, it, expect, vi } from 'vitest'
+import { PaperCard } from '../PaperCard'
+
+vi.mock('../../../stores/useSocialStore', () => ({
+  useSocialStore: {
+    getState: () => ({
+      endorsements: {},
+      likes: {},
+      addEndorsement: vi.fn(),
+      toggleLike: vi.fn()
+    })
+  }
+}))
+
+describe('PaperCard', () => {
+  it('renders basic info and calls store on request', () => {
+    render(<PaperCard title="Test Paper" author="Alice" endorsements={0} />)
+    expect(screen.getByText('Test Paper')).toBeTruthy()
+    const btn = screen.getByRole('button', { name: /request endorsement/i })
+    fireEvent.click(btn)
+    // Replace with concrete assertions once store mocks are wired
+    expect(true).toBe(true)
+  })
+})
+```
+
+Notes
+- Ensure `vitest`, `@testing-library/react`, and `@testing-library/jest-dom` are installed and configured in `package.json`.
+- Tests are intentionally scaffolded and should be adapted to the actual store wiring (zustand or context).