Add Harbor fallback for catalog and search endpoints

Harbor denies access to the V2 _catalog endpoint for robot accounts
(scope registry:catalog:* returns an empty JWT). This adds automatic
Harbor detection and falls back to the native Harbor project API
(/api/v2.0/projects/{name}/repositories) for both catalog listing
and image search.

- Detect Harbor via WWW-Authenticate header + /api/v2.0/ping (cached 5min)
- List repositories through Harbor project API with pagination
- Search repositories using Harbor's q=name=~ filter
- Transparent fallback: no configuration change required

Fixes #360

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

src/routes/api/registry/search/+server.ts

@@ -1,7 +1,7 @@
 import { json } from '@sveltejs/kit';
 import type { RequestHandler } from './$types';
 import { getRegistry } from '$lib/server/db';
-import { getRegistryAuth, parseRegistryUrl } from '$lib/server/docker';
+import { getRegistryAuth, isHarborRegistry, harborSearchRepositories, parseRegistryUrl } from '$lib/server/docker';
 
 interface SearchResult {
 	name: string;
@@ -127,6 +127,12 @@ async function tryDirectImageLookup(registry: any, imageName: string): Promise<b
 
 // Search through catalog (slow for large registries, limited to first few pages)
 async function searchCatalog(registry: any, term: string, limit: number): Promise<string[]> {
+	// Fallback Harbor : utiliser l'API projet native pour la recherche
+	if (await isHarborRegistry(registry.url)) {
+		const { path: orgPath } = parseRegistryUrl(registry.url);
+		return harborSearchRepositories(registry, term, orgPath, limit);
+	}
+
 	// Note: orgPath could be used here to filter results, but search is already term-based
 	const { baseUrl, authHeader } = await getRegistryAuth(registry, 'registry:catalog:*');