feat: collection picker in product creation flow

- API /api/creation/collections liste toutes les collections Shopify
- Détection automatique depuis la colonne ID FAMILLE du Sheets
- Sélecteur avec recherche si absente ou pour modifier
- Collection affichée dans l'écran de confirmation
- collectionOverride passé à l'exécution comme fallback

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

src/app/api/creation/collections/route.ts

@@ -0,0 +1,32 @@
+import { NextResponse } from 'next/server'
+import { getServerSession } from 'next-auth'
+import { authOptions } from '@/lib/auth'
+
+const API_VERSION = '2024-01'
+
+export async function GET() {
+  const session = await getServerSession(authOptions)
+  if (!session) return NextResponse.json({ error: 'Non authentifié' }, { status: 401 })
+
+  const domain = process.env.SHOPIFY_STORE_DOMAIN
+  const token = process.env.SHOPIFY_ADMIN_API_TOKEN
+  if (!domain || !token) return NextResponse.json({ error: 'Config Shopify manquante' }, { status: 500 })
+
+  const baseUrl = `https://${domain}/admin/api/${API_VERSION}`
+  const headers = { 'X-Shopify-Access-Token': token, 'Content-Type': 'application/json' }
+
+  // Récupère custom collections + smart collections
+  const [customRes, smartRes] = await Promise.all([
+    fetch(`${baseUrl}/custom_collections.json?limit=250&fields=id,title`, { headers }),
+    fetch(`${baseUrl}/smart_collections.json?limit=250&fields=id,title`, { headers }),
+  ])
+
+  const custom = customRes.ok ? (await customRes.json()).custom_collections as { id: number; title: string }[] : []
+  const smart = smartRes.ok ? (await smartRes.json()).smart_collections as { id: number; title: string }[] : []
+
+  const collections = [...custom, ...smart]
+    .map(c => ({ id: String(c.id), title: c.title }))
+    .sort((a, b) => a.title.localeCompare(b.title))
+
+  return NextResponse.json({ collections })
+}

src/app/api/creation/execute/route.ts

@@ -20,9 +20,10 @@ export async function POST(req: NextRequest) {
   }
 
   const userId = (session.user as { id: string }).id
-  const body = await req.json().catch(() => ({})) as { resolutions?: MetafieldResolution[]; tab?: string }
+  const body = await req.json().catch(() => ({})) as { resolutions?: MetafieldResolution[]; tab?: string; collectionOverride?: string }
   const resolutions: MetafieldResolution[] = body.resolutions ?? []
   const tabFilter: string | undefined = body.tab ?? undefined
+  const collectionOverride: string | undefined = body.collectionOverride ?? undefined
   const resolutionMap = new Map<string, MetafieldResolution>(resolutions.map(r => [r.columnHeader, r]))
 
   const stream = new ReadableStream({
@@ -83,7 +84,8 @@ export async function POST(req: NextRequest) {
               weightKg: product.weightKg,
               status: 'active',
             })
-            if (product.collectionId) await addProductToCollection(shopifyId, product.collectionId)
+            const effectiveCollectionId = product.collectionId || collectionOverride || ''
+            if (effectiveCollectionId) await addProductToCollection(shopifyId, effectiveCollectionId)
             if (product.subCollectionId) await addProductToCollection(shopifyId, product.subCollectionId)
             send({ type: 'progress', current: i + 1, total, tab: product.tab, title: product.title, step: 'Métachamps…' })
             for (const [colHeader, value] of Object.entries(product.specificFields)) {