feat: export middleware chain

src/index.ts

@@ -31,4 +31,7 @@ export { mutableSignal } from './utils/mutable-signal';
 export type { RNG } from './utils/rng';
 export { createRNG, Mulberry32RNG } from './utils/rng';
 
+export type {MiddlewareChain} from './utils/middleware'
+export { createMiddlewareChain } from './utils/middleware';
+
 export * from '@preact/signals-core';