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/NOTES.md

@@ -14,7 +14,7 @@ Syncs to Claude Design project **Reactive Resume** (`3c0f6556-050a-41e5-9886-c3f
 ## Card scope
 
 - The package exports **202 symbols** (39 primary components + 163 compound sub-parts). User chose **~40 primary cards**: `cfg.componentSrcMap` nulls the 163 sub-parts. All 202 stay importable from `window.RRUI` (the bundle exports everything regardless of the card list), so previews compose sub-parts (`RRUI.DialogContent`, etc.) freely.
-- Multi-primary files represented by one card: `combobox.tsx`→ComboboxRoot, `form.tsx`→FormItem, `resizable.tsx`→ResizableGroup, `sonner.tsx`→Toaster.
+- Multi-primary files represented by one card: `combobox.tsx`→ComboboxRoot, `form.tsx`→FormItem, `resizable.tsx`→ResizableGroup, `toast.tsx`→Toaster.
 
 ## Preview authoring conventions (calibrated on Button / Alert / Dialog)
 

.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>
 	);
 };