chore: upgrade to pnpm v12, vitest v5 and resolve deprecated subdependencies

src/app/api/online/count/stream/route.ts

@@ -103,6 +103,7 @@ export async function GET(req: Request) {
 		headers: {
 			"content-type": "text/event-stream; charset=utf-8",
 			"cache-control": "no-store, no-transform",
+			"x-accel-buffering": "no",
 			connection: "keep-alive",
 		},
 	});