feat(ui): add a Base UI toast component

Adds the toast primitive that replaces sonner, along with its design-sync card
mapping. Nothing consumes it yet; the call sites move over next.

.design-sync/previews/Toaster.tsx

@@ -1,19 +1,20 @@
 import { useEffect } from "react";
-import { toast } from "sonner";
-import { Toaster } from "@reactive-resume/ui/components/sonner";
+import { Toaster, toast } from "@reactive-resume/ui/components/toast";
 
 // Toaster is the toast host. Fire a persistent toast on mount so the card
 // shows a real notification instead of an empty portal.
 export const Notification = () => {
 	useEffect(() => {
-		toast.success("Resume published", {
+		toast.add({
+			type: "success",
+			title: "Resume published",
 			description: "“Software Engineer” is now live at rxresume.me/jane-doe.",
-			duration: Number.POSITIVE_INFINITY,
+			timeout: 0,
 		});
 	}, []);
 	return (
 		<div style={{ minHeight: 140 }}>
-			<Toaster position="top-center" />
+			<Toaster />
 		</div>
 	);
 };