Migrate icon buttons to Button component and simplify size variants

Replace raw <button> elements with Button variant="ghost" in stat-block
panel, toast, player modals. Add icon-sm size variant (h-6 w-6) for
compact contexts. Consolidate text button sizes into a single default
(h-8 px-3), removing the redundant sm variant. Add size prop to
ConfirmButton for consistent sizing.

Button now has three sizes: default (text), icon, icon-sm.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

apps/web/src/components/toast.tsx

@@ -1,6 +1,7 @@
 import { X } from "lucide-react";
 import { useEffect } from "react";
 import { createPortal } from "react-dom";
+import { Button } from "./ui/button.js";
 
 interface ToastProps {
 	message: string;
@@ -33,13 +34,14 @@ export function Toast({
 						/>
 					</div>
 				)}
-				<button
-					type="button"
+				<Button
+					variant="ghost"
+					size="icon-sm"
 					onClick={onDismiss}
-					className="text-muted-foreground hover:text-hover-neutral"
+					className="text-muted-foreground"
 				>
 					<X className="h-3 w-3" />
-				</button>
+				</Button>
 			</div>
 		</div>,
 		document.body,