feat(books): édition des métadonnées livres et séries + champ authors multi-valeurs

- Nouveaux endpoints PATCH /books/:id et PATCH /libraries/:id/series/:name pour éditer les métadonnées
- GET /libraries/:id/series/:name/metadata pour récupérer les métadonnées de série
- Ajout du champ `authors` (Vec<String>) sur les structs Book/BookDetails
- 3 migrations : table series_metadata, colonne authors sur series_metadata et books
- Composants EditBookForm et EditSeriesForm dans le backoffice
- Routes API Next.js correspondantes

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

apps/backoffice/lib/api.ts

@@ -62,6 +62,7 @@ export type BookDto = {
   format: string | null;
   title: string;
   author: string | null;
+  authors: string[];
   series: string | null;
   volume: number | null;
   language: string | null;
@@ -484,6 +485,54 @@ export async function fetchStats() {
   return apiFetch<StatsResponse>("/stats");
 }
 
+export type UpdateBookRequest = {
+  title: string;
+  author: string | null;
+  authors: string[];
+  series: string | null;
+  volume: number | null;
+  language: string | null;
+};
+
+export async function updateBook(bookId: string, data: UpdateBookRequest) {
+  return apiFetch<BookDto>(`/books/${bookId}`, {
+    method: "PATCH",
+    body: JSON.stringify(data),
+  });
+}
+
+export type SeriesMetadataDto = {
+  authors: string[];
+  description: string | null;
+  publishers: string[];
+  start_year: number | null;
+  book_author: string | null;
+  book_language: string | null;
+};
+
+export async function fetchSeriesMetadata(libraryId: string, seriesName: string) {
+  return apiFetch<SeriesMetadataDto>(
+    `/libraries/${libraryId}/series/${encodeURIComponent(seriesName)}/metadata`
+  );
+}
+
+export type UpdateSeriesRequest = {
+  new_name: string;
+  authors: string[];
+  author?: string | null;
+  language?: string | null;
+  description: string | null;
+  publishers: string[];
+  start_year: number | null;
+};
+
+export async function updateSeries(libraryId: string, seriesName: string, data: UpdateSeriesRequest) {
+  return apiFetch<{ updated: number }>(`/libraries/${libraryId}/series/${encodeURIComponent(seriesName)}`, {
+    method: "PATCH",
+    body: JSON.stringify(data),
+  });
+}
+
 export async function markSeriesRead(seriesName: string, status: "read" | "unread" = "read") {
   return apiFetch<{ updated: number }>("/series/mark-read", {
     method: "POST",