feat(api,shared): métadonnées multi-providers et automatisation des scans/enrichissements

Chaîne de résolution metadata (local, Open Library, Google Books, BNF)
avec activation/priorité/clé API par provider, colonnes isbn13 et
identifiers sur les livres, et intégration au scanner pour compléter
métadonnées et jaquettes manquantes. Module automation: réglages
persistés, planifications scan/enrichissement et déclenchement manuel,
exposés via des endpoints admin.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

apps/api/src/metadata/adapters/google-books.provider.ts

@@ -0,0 +1,47 @@
+import { Injectable } from "@nestjs/common";
+import { MetadataLookup, MetadataMatch, MetadataProvider, MetadataProviderConfig } from "../metadata.types.js";
+
+@Injectable()
+export class GoogleBooksProvider implements MetadataProvider {
+  readonly id = "googlebooks" as const;
+
+  async lookup(lookup: MetadataLookup, config: MetadataProviderConfig): Promise<MetadataMatch | null> {
+    const query = lookup.identifiers.isbn13
+      ? `isbn:${lookup.identifiers.isbn13}`
+      : `intitle:${lookup.title}${lookup.author ? `+inauthor:${lookup.author}` : ""}`;
+    const url = new URL("https://www.googleapis.com/books/v1/volumes");
+    url.searchParams.set("q", query);
+    url.searchParams.set("maxResults", "1");
+    if (config.apiKey) url.searchParams.set("key", config.apiKey);
+
+    const response = await fetch(url, { signal: AbortSignal.timeout(4000) });
+    if (!response.ok) return null;
+    const data = (await response.json()) as { items?: Array<{ volumeInfo?: Record<string, unknown> }> };
+    const info = data.items?.[0]?.volumeInfo;
+    if (!info) return null;
+    return {
+      title: stringValue(info.title) ?? undefined,
+      author: arrayJoin(info.authors),
+      description: stringValue(info.description),
+      language: stringValue(info.language),
+      publisher: stringValue(info.publisher),
+      publishedDate: stringValue(info.publishedDate),
+      isbn: isbnFromIndustryIdentifiers(info.industryIdentifiers)
+    };
+  }
+}
+
+function stringValue(value: unknown): string | null {
+  return typeof value === "string" && value.trim() ? value.trim() : null;
+}
+
+function arrayJoin(value: unknown): string | null {
+  return Array.isArray(value) && value.length ? value.map(String).join(", ") : null;
+}
+
+function isbnFromIndustryIdentifiers(value: unknown): string | null {
+  if (!Array.isArray(value)) return null;
+  const isbn13 = value.find((entry) => entry?.type === "ISBN_13")?.identifier;
+  const isbn10 = value.find((entry) => entry?.type === "ISBN_10")?.identifier;
+  return stringValue(isbn13) ?? stringValue(isbn10);
+}