feat(frontend): Phase 1.1 grid layout with Phase 2 pre-allocation and tests

App layout uses CSS Grid with Top-Left video placeholder (Film icon), Top-Right empty container for Phase 1.2 input, and Bottom full-width container for Phase 1.2 response. Includes Layout test verifying Phase 2 placeholder text and API client tests verifying baseURL and mocked endpoint calls.

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

frontend/src/App.tsx

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+import React from 'react'
+import { QueryClientProvider } from '@tanstack/react-query'
+import { queryClient } from './lib/queries'
+import { Film } from 'lucide-react'
+
+const VideoPlaceholder: React.FC = () => {
+  return (
+    <div className="h-full flex items-center justify-center bg-white/50">
+      <div className="text-center space-y-2">
+        <Film className="mx-auto w-12 h-12 text-gray-600" />
+        <div className="text-gray-700 font-semibold">Video upload coming in Phase 2</div>
+      </div>
+    </div>
+  )
+}
+
+const RightTop: React.FC = () => {
+  return <div className="h-full border rounded border-dashed border-gray-300" />
+}
+
+const BottomArea: React.FC = () => {
+  return <div className="border border-dashed border-gray-300 rounded h-full" />
+}
+
+const AppLayout: React.FC = () => {
+  return (
+    <div className="h-screen grid grid-rows-[1fr_auto] grid-cols-2">
+      <div className="border-r border-b border-gray-200 p-4">
+        <VideoPlaceholder />
+      </div>
+      <div className="border-b border-gray-200 p-4">
+        <RightTop />
+      </div>
+      <div className="col-span-2 p-4 border-t border-gray-200">
+        <BottomArea />
+      </div>
+    </div>
+  )
+}
+
+export default function App(): JSX.Element {
+  return (
+    <QueryClientProvider client={queryClient}>
+      <AppLayout />
+    </QueryClientProvider>
+  )
+}

frontend/src/main.tsx

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+import React from 'react'
+import { createRoot } from 'react-dom/client'
+import App from './App'
+import './styles.css'
+
+const root = createRoot(document.getElementById('root')!)
+root.render(
+  <React.StrictMode>
+    <App />
+  </React.StrictMode>
+)

frontend/src/test/components/Layout.test.tsx

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+import React from 'react'
+import { render, screen } from '@testing-library/react'
+import App from '../../App'
+
+describe('Layout', () => {
+  test('renders VideoPlaceholder with Phase 2 text', () => {
+    render(<App />)
+    const text = screen.getByText(/Video upload coming in Phase 2/i)
+    expect(text).toBeInTheDocument()
+  })
+})

frontend/src/test/lib/api.test.ts

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+import { describe, it, expect, vi, beforeEach } from 'vitest'
+import { apiClient, queryDocument, ingestDocument } from '../../lib/api'
+
+describe('API client basics', () => {
+  it('has a baseURL containing /api/v1', () => {
+    expect(apiClient.defaults.baseURL).toContain('/api/v1')
+  })
+
+  it('queryDocument posts and returns data', async () => {
+    const mockPost = vi.spyOn(apiClient, 'post')
+    mockPost.mockResolvedValueOnce({ data: { keywords: [], answer: '', sources: [] } })
+    const res = await queryDocument({ question: 'test' })
+    expect(res).toHaveProperty('answer')
+  })
+
+  it('ingestDocument posts and returns data', async () => {
+    const mockPost = vi.spyOn(apiClient, 'post')
+    mockPost.mockResolvedValueOnce({ data: { document_id: 'doc1', chunk_count: 1, filename: 'a.txt' } })
+    const file = new File(['data'], 'a.txt', { type: 'text/plain' })
+    const res = await ingestDocument(file)
+    expect(res).toHaveProperty('document_id')
+  })
+})

frontend/src/test/setup.ts

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+import '@testing-library/jest-dom'