perf: prevent import hanging with timeouts and batching

- verifyAndFixInteractionModesCount: paginated DB queries (500/batch)
  instead of loading all items into memory at once
- withFurniDataLock: add 60s chain timeout to prevent deadlocks
  when a lock holder stalls or crashes
- withGamedataLock: same timeout protection for gamedata locks
- conversion-pool: add 60s per-job timeout, fall back to main thread
- furni/batch: abort signal + post_import progress events + skip
  post-import steps when client disconnects
- furni/batch-regen: abort signal + early exit when disconnected
- clone/sync-all: pre-fetch furnidata once per source instead of
  per item (eliminates 2000+ redundant fetches)
- sse-client: add 60s idle timeout to prevent infinite hangs

src/app/api/admin/import/furni/batch-regen/route.ts

@@ -47,9 +47,16 @@ export const POST = withAdmin(
 		const { swfDir, nitroDir } = await getFurniAssetDirs();
 		const encoder = new TextEncoder();
 
+		// Wire client disconnect to abort controller
+		let aborted = false;
+		request.signal.addEventListener("abort", () => {
+			aborted = true;
+		});
+
 		const stream = new ReadableStream({
 			async start(controller) {
 				const send = (data: unknown) => {
+					if (aborted) return;
 					try {
 						controller.enqueue(
 							encoder.encode(`data: ${JSON.stringify(data)}\n\n`),
@@ -240,6 +247,18 @@ export const POST = withAdmin(
 					await new Promise((r) => setImmediate(r));
 				}
 
+				if (aborted) {
+					send({
+						type: "regen_complete",
+						succeeded,
+						failed,
+						skipped,
+						aborted: true,
+					});
+					controller.close();
+					return;
+				}
+
 				// Batch write FurnitureData.json
 				if (furniDataEntries.length > 0) {
 					try {
@@ -291,25 +310,27 @@ export const POST = withAdmin(
 					);
 				}
 
-				send({
-					type: "regen_complete",
-					succeeded,
-					failed,
-					skipped,
-					furniDataAdded: furniDataEntries.length,
-					ownershipFixed: ownership.fixed,
-					nitrosSynced: assetsSynced.copiedNitros,
-					iconsSynced: assetsSynced.copiedIcons,
-					furniDataFixedIds: furniReconcile.fixedIds,
-					furniDataMissing: furniReconcile.missing,
-					furniDataConflicts: furniReconcile.conflicts,
-					offerRebuildChecked: offerRebuild.checked,
-					offerRebuildFixed: offerRebuild.fixed,
-					spriteChecked: spriteVerify.checked,
-					spriteFixed: spriteVerify.fixed,
-					languages,
-					duration: Date.now() - startTime,
-				});
+				if (!aborted) {
+					send({
+						type: "regen_complete",
+						succeeded,
+						failed,
+						skipped,
+						furniDataAdded: furniDataEntries.length,
+						ownershipFixed: ownership.fixed,
+						nitrosSynced: assetsSynced.copiedNitros,
+						iconsSynced: assetsSynced.copiedIcons,
+						furniDataFixedIds: furniReconcile.fixedIds,
+						furniDataMissing: furniReconcile.missing,
+						furniDataConflicts: furniReconcile.conflicts,
+						offerRebuildChecked: offerRebuild.checked,
+						offerRebuildFixed: offerRebuild.fixed,
+						spriteChecked: spriteVerify.checked,
+						spriteFixed: spriteVerify.fixed,
+						languages,
+						duration: Date.now() - startTime,
+					});
+				}
 
 				controller.close();
 			},