feat(ui): formulaire de création de carte avec navigation (F-05)

CardForm en mode création : champs question/réponse/thème, validation
HTML + affichage derreur API, soumission via cardsApi.create puis
redirection vers le détail de la carte créée (next/navigation).

src/components/card-form.test.tsx

@@ -0,0 +1,38 @@
+import { render, screen } from '@testing-library/react'
+import userEvent from '@testing-library/user-event'
+import { beforeEach, describe, expect, it, vi } from 'vitest'
+import { CardForm } from './card-form'
+
+vi.mock('@/lib/api-client', () => ({
+  ApiClientError: class extends Error { status = 0 },
+  cardsApi: { create: vi.fn(), update: vi.fn() },
+}))
+
+const routerMock = { push: vi.fn(), refresh: vi.fn() }
+vi.mock('next/navigation', () => ({
+  useRouter: () => routerMock,
+}))
+
+import { cardsApi } from '@/lib/api-client'
+
+beforeEach(() => {
+  vi.mocked(cardsApi.create).mockReset()
+  vi.mocked(cardsApi.update).mockReset()
+  routerMock.push.mockReset()
+  routerMock.refresh.mockReset()
+})
+
+it('crée une carte puis navigue vers son détail (F-05)', async () => {
+  vi.mocked(cardsApi.create).mockResolvedValue({ id: 'c1' } as never)
+  render(<CardForm mode="create" />)
+  await userEvent.type(screen.getByLabelText('Question'), 'Cest quoi un commit ?')
+  await userEvent.type(screen.getByLabelText('Réponse'), 'Un snapshot')
+  await userEvent.type(screen.getByLabelText('Thème'), 'git')
+  await userEvent.click(screen.getByRole('button', { name: 'Créer la carte' }))
+  expect(vi.mocked(cardsApi.create)).toHaveBeenCalledWith({
+    question: 'Cest quoi un commit ?',
+    response: 'Un snapshot',
+    theme: 'git',
+  })
+  await screen.findByText('Enregistrement…')
+})

src/components/card-form.tsx

@@ -0,0 +1,95 @@
+'use client'
+
+import { useRouter } from 'next/navigation'
+import { useState } from 'react'
+import type { CardInput } from '@/domain/card'
+import { ApiClientError, cardsApi } from '@/lib/api-client'
+
+interface CardFormProps {
+  mode: 'create' | 'edit'
+  cardId?: string
+  initial?: CardInput
+}
+
+export function CardForm({ mode, cardId, initial }: CardFormProps) {
+  const router = useRouter()
+  const [question, setQuestion] = useState(initial?.question ?? '')
+  const [response, setResponse] = useState(initial?.response ?? '')
+  const [theme, setTheme] = useState(initial?.theme ?? '')
+  const [error, setError] = useState<string | null>(null)
+  const [saving, setSaving] = useState(false)
+
+  async function handleSubmit(e: React.FormEvent) {
+    e.preventDefault()
+    setSaving(true)
+    setError(null)
+    const input: CardInput = { question, response, theme }
+    try {
+      if (mode === 'create') {
+        const card = await cardsApi.create(input)
+        router.push(`/cards/${card.id}`)
+        router.refresh()
+      } else if (cardId) {
+        await cardsApi.update(cardId, input)
+        router.push(`/cards/${cardId}`)
+        router.refresh()
+      }
+    } catch (err) {
+      setError(err instanceof ApiClientError ? err.message : 'Impossible de sauvegarder la carte')
+      setSaving(false)
+    }
+  }
+
+  return (
+    <form onSubmit={handleSubmit} className="space-y-4">
+      {error && (
+        <p role="alert" className="text-red-600">{error}</p>
+      )}
+      <div>
+        <label htmlFor="question" className="block text-sm font-medium text-slate-700">
+          Question
+        </label>
+        <input
+          id="question"
+          value={question}
+          onChange={(e) => setQuestion(e.target.value)}
+          required
+          className="mt-1 w-full rounded-lg border border-slate-300 px-3 py-2"
+        />
+      </div>
+      <div>
+        <label htmlFor="response" className="block text-sm font-medium text-slate-700">
+          Réponse
+        </label>
+        <textarea
+          id="response"
+          value={response}
+          onChange={(e) => setResponse(e.target.value)}
+          required
+          className="mt-1 w-full rounded-lg border border-slate-300 px-3 py-2"
+        />
+      </div>
+      <div>
+        <label htmlFor="theme" className="block text-sm font-medium text-slate-700">
+          Thème
+        </label>
+        <input
+          id="theme"
+          value={theme}
+          onChange={(e) => setTheme(e.target.value)}
+          required
+          className="mt-1 w-full rounded-lg border border-slate-300 px-3 py-2"
+        />
+      </div>
+      <div className="flex items-center gap-3">
+        <button
+          type="submit"
+          disabled={saving}
+          className="rounded-lg bg-slate-900 px-4 py-2 text-sm font-medium text-white hover:bg-slate-700 disabled:opacity-50"
+        >
+          {saving ? 'Enregistrement…' : mode === 'create' ? 'Créer la carte' : 'Enregistrer'}
+        </button>
+      </div>
+    </form>
+  )
+}