Add clone source selection to Studio furni browser

Allow the admin Studio to browse and import furniture from custom retro
hotel sources, not just official Habbo furnidata.

- GET /api/admin/import/furni?source=<id> lists a clone source's
  furnidata (via getCloneList) and returns a per-item iconUrl from the
  source's iconBaseUrl so previews render correctly
- Studio client gets a source selector dropdown (official Habbo plus all
  configured clone_sources) that resets the selection and reloads the
  list when switched
- Single and batch imports now send sourceId so SWF/nitro/icon assets
  are fetched from the selected hotel's CDN
- Preview images prefer the source iconUrl with the existing fallback
  chain; header shows the active source name

src/app/api/admin/import/furni/route.ts

@@ -6,6 +6,7 @@ import { apiError, apiOk } from "@/lib/api-response";
 import { CatalogPages, db, ItemsBase } from "@/lib/db";
 import { PERMS } from "@/lib/permissions";
 import { logAudit } from "@/lib/services/audit";
+import { getCloneList } from "@/lib/services/clone-import";
 import { getSource } from "@/lib/services/clone-sources";
 import { getFurniAssetDirs } from "@/lib/services/furni-asset-dirs";
 import {
@@ -213,6 +214,64 @@ export const GET = withAdmin(
 		const search = request.nextUrl.searchParams.get("search") || "";
 		const page = parseInt(request.nextUrl.searchParams.get("page") || "1", 10);
 
+		// ── Browse a custom clone source (retro hotel furnidata) ────────
+		const sourceId = request.nextUrl.searchParams.get("source");
+		if (sourceId) {
+			const source = await getSource(sourceId);
+			if (!source) return apiError("Source not found", 404);
+
+			const { items, meta } = await getCloneList({
+				source,
+				search,
+				page,
+				perPage: 50,
+				filter: "all",
+			});
+
+			const sourceIconBase = source.iconBaseUrl?.trim().replace(/\/+$/, "");
+			const enriched = items.map((item) => {
+				const imported = item.present;
+				let nitroExists = false;
+				if (imported) {
+					const starIdx = item.classname.indexOf("*");
+					const base =
+						starIdx !== -1
+							? item.classname.substring(0, starIdx)
+							: item.classname;
+					const p = path.join(
+						/*turbopackIgnore: true*/ nitroDir,
+						`${base}.nitro`,
+					);
+					nitroExists = existsSync(/*turbopackIgnore: true*/ p);
+				}
+				return {
+					id: item.id,
+					classname: item.classname,
+					type: item.itemType === "i" ? "wallitem" : "flooritem",
+					name: item.name,
+					description: item.description,
+					revision: 0,
+					category: String(item.category ?? ""),
+					alreadyImported: imported,
+					nitroExists,
+					iconUrl: sourceIconBase
+						? `${sourceIconBase}/${encodeURIComponent(item.classname)}_icon.png`
+						: undefined,
+				};
+			});
+
+			return apiOk({
+				items: enriched,
+				source: { id: source.id, name: source.name },
+				meta: {
+					currentPage: meta.page,
+					lastPage: Math.max(Math.ceil(meta.total / meta.perPage), 1),
+					total: meta.total,
+					perPage: meta.perPage,
+				},
+			});
+		}
+
 		// Pull every imported classname once so we can both (a) sort non-imported
 		// items to the top *before* pagination and (b) skip the per-page lookup
 		// below. Single-column indexed query — fast even at 10k+ rows.