feat: fix author search, add edit modals, settings tabs & search resync

- Fix Meilisearch indexing to use authors[] array instead of scalar author field
- Join series_metadata to include series-level authors in search documents
- Configure searchable attributes (title, authors, series) in Meilisearch
- Convert EditSeriesForm and EditBookForm from inline forms to modals
- Add tabbed navigation (General / Integrations) to Settings page
- Add Force Search Resync button (POST /settings/search/resync)

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

apps/backoffice/lib/api.ts

@@ -87,7 +87,7 @@ export type SearchHitDto = {
   id: string;
   library_id: string;
   title: string;
-  author: string | null;
+  authors: string[];
   series: string | null;
   volume: number | null;
   kind: string;
@@ -406,6 +406,12 @@ export async function getThumbnailStats() {
   return apiFetch<ThumbnailStats>("/settings/thumbnail/stats");
 }
 
+export async function forceSearchResync() {
+  return apiFetch<{ success: boolean; message: string }>("/settings/search/resync", {
+    method: "POST",
+  });
+}
+
 export async function convertBook(bookId: string) {
   return apiFetch<IndexJobDto>(`/books/${bookId}/convert`, { method: "POST" });
 }