feat(notes): wire app with floating add button

src/components/FloatingButton.test.tsx

@@ -0,0 +1,26 @@
+import { fireEvent, render, screen } from '@testing-library/react'
+import { describe, expect, it, vi } from 'vitest'
+import FloatingButton from './FloatingButton'
+
+describe('FloatingButton', () => {
+  it('renders a + button', () => {
+    render(<FloatingButton onClick={vi.fn()} />)
+
+    expect(screen.getByRole('button', { name: 'Créer une note' })).toHaveTextContent('+')
+  })
+
+  it('calls onClick when clicked', () => {
+    const onClick = vi.fn()
+    render(<FloatingButton onClick={onClick} />)
+
+    fireEvent.click(screen.getByRole('button', { name: 'Créer une note' }))
+
+    expect(onClick).toHaveBeenCalled()
+  })
+
+  it('uses a custom label when provided', () => {
+    render(<FloatingButton onClick={vi.fn()} label="Ajouter" />)
+
+    expect(screen.getByRole('button', { name: 'Ajouter' })).toBeInTheDocument()
+  })
+})