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/create-player-modal.tsx

@@ -100,13 +100,14 @@ export function CreatePlayerModal({
 					<h2 className="text-lg font-semibold text-foreground">
 						{isEdit ? "Edit Player" : "Create Player"}
 					</h2>
-					<button
-						type="button"
+					<Button
+						variant="ghost"
+						size="icon"
 						onClick={onClose}
-						className="text-muted-foreground hover:text-hover-neutral transition-colors"
+						className="text-muted-foreground"
 					>
 						<X size={20} />
-					</button>
+					</Button>
 				</div>
 
 				<form onSubmit={handleSubmit} className="flex flex-col gap-4">