Better ts support (cherry-pick #107)

Author: zerodevx

src/lib/index.js

@@ -1,2 +1,6 @@
 export { default as SvelteToast } from './SvelteToast.svelte'
 export { toast } from './stores.js'
+
+/**
+ * @typedef {import('./stores.js').SvelteToastOptions} SvelteToastOptions
+ */