perf(imaging): add s-maxage so Cloudflare caches avatar images

Avatars are proxied from the slow Habbo upstream on every request
(~350ms each) and Cloudflare was serving them as DYNAMIC because the
Cache-Control had no s-maxage. Add s-maxage=86400 + stale-while-revalidate
so edge/CDN caches avatars and repeats are served instantly.

src/app/imaging/route.ts

@@ -90,7 +90,10 @@ export async function GET(request: NextRequest) {
 			status: 200,
 			headers: {
 				"Content-Type": contentType,
-				"Cache-Control": "public, max-age=3600",
+				// s-maxage lets Cloudflare/edge cache avatars (currently DYNAMIC),
+				// stale-while-revalidate keeps them fresh without blocking requests.
+				"Cache-Control":
+					"public, max-age=3600, s-maxage=86400, stale-while-revalidate=86400",
 				"Access-Control-Allow-Origin": "*",
 			},
 		});