fix: prevent import hanging by adding abort signals and idle timeouts

- Furni batch: wire request.signal to abort controller, send post_import
  progress events, skip post-import steps when aborted
- Clone sync-all: pre-fetch furnidata once per source instead of per item
  (eliminates 2000+ redundant DB reads + HTTP requests)
- SSE client: add 60s idle timeout to prevent infinite hangs when server
  stops responding

src/app/api/admin/import/clone/sync-all/route.ts

@@ -6,6 +6,7 @@ import { logAudit } from "@/lib/services/audit";
 import {
 	cloneSingleFurni,
 	fetchSourceFurnidata,
+	type SourceFurni,
 } from "@/lib/services/clone-import";
 import { listSources } from "@/lib/services/clone-sources";
 import {
@@ -39,6 +40,20 @@ export const POST = withAdmin(
 			);
 		}
 
+		// Pre-fetch furnidata ONCE per source and build a lookup map.
+		// The old code re-fetched inside the worker loop for every item,
+		// causing 2000+ redundant DB reads + HTTP requests.
+		const sourceFurniDataMap = new Map<string, Map<string, SourceFurni>>();
+
+		for (const source of sources) {
+			try {
+				const entries = await fetchSourceFurnidata(source.furnidataUrl);
+				const byClassname = new Map(entries.map((e) => [e.classname, e]));
+				sourceFurniDataMap.set(source.id, byClassname);
+			} catch {}
+		}
+
+		// Collect all missing items using pre-fetched data
 		const allItems: Array<{
 			classname: string;
 			sourceName: string;
@@ -46,14 +61,10 @@ export const POST = withAdmin(
 		}> = [];
 
 		for (const source of sources) {
-			let entries: Awaited<ReturnType<typeof fetchSourceFurnidata>>;
-			try {
-				entries = await fetchSourceFurnidata(source.furnidataUrl);
-			} catch {
-				continue;
-			}
+			const byClassname = sourceFurniDataMap.get(source.id);
+			if (!byClassname) continue;
 
-			const classnames = entries.map((e) => e.classname);
+			const classnames = [...byClassname.keys()];
 			if (classnames.length === 0) continue;
 
 			const rows = await db
@@ -62,10 +73,10 @@ export const POST = withAdmin(
 				.where(inArray(ItemsBase.itemName, classnames));
 			const have = new Set(rows.map((r) => r.item_name));
 
-			for (const entry of entries) {
-				if (!have.has(entry.classname)) {
+			for (const classname of classnames) {
+				if (!have.has(classname)) {
 					allItems.push({
-						classname: entry.classname,
+						classname,
 						sourceName: source.name,
 						sourceId: source.id,
 					});
@@ -106,29 +117,30 @@ export const POST = withAdmin(
 			itemType: string;
 		}> = [];
 
+		// Source lookup cache — pre-fetched above, no need to re-fetch per item
+		const sourceMap = new Map(sources.map((s) => [s.id, s]));
+
 		return runSseBatch({
 			items: allItems,
 			concurrency: 10,
 			signal: request.signal,
 			labelOf: (it) => `${it.sourceName}/${it.classname}`,
 			worker: async (it, _index, report) => {
-				const allSrc = await listSources();
-				const source = allSrc.find((s) => s.id === it.sourceId);
+				const source = sourceMap.get(it.sourceId);
 				if (!source) {
 					return { ok: false, error: "source not found" };
 				}
 
-				let allEntries: Awaited<ReturnType<typeof fetchSourceFurnidata>>;
-				try {
-					allEntries = await fetchSourceFurnidata(source.furnidataUrl);
-				} catch (err) {
+				// Use pre-fetched furnidata instead of re-fetching
+				const byClassname = sourceFurniDataMap.get(it.sourceId);
+				if (!byClassname) {
 					return {
 						ok: false,
-						error: `furnidata fetch failed: ${(err as Error).message}`,
+						error: "furnidata not available for this source",
 					};
 				}
 
-				const entry = allEntries.find((e) => e.classname === it.classname);
+				const entry = byClassname.get(it.classname);
 				if (!entry) {
 					return {
 						ok: false,