fix: remove always-on underline from notification cross-links

underline decoration-accent/60 was forcing a permanent underline.
The global a:hover rule already handles underline + accent color on hover.

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

frontend/src/lib/components/DashboardMentions.svelte

@@ -49,7 +49,7 @@ let { mentions }: Props = $props();
 		<div class="mt-4 border-t border-line pt-4">
 			<a
 				href="/notifications"
-				class="text-sm font-medium text-ink-2 underline decoration-accent/60 transition-colors hover:text-ink hover:decoration-accent"
+				class="text-sm font-medium text-ink-2 transition-colors hover:text-ink"
 				>{m.notification_history_view_link()}</a
 			>
 		</div>

frontend/src/routes/notifications/+page.svelte

@@ -94,7 +94,7 @@ function typeBadgeLabel(type: NotificationItem['type']): string {
 				<form method="POST" action="?/mark-all">
 					<button
 						type="submit"
-						class="text-sm font-medium text-ink-2 underline decoration-accent/60 transition-colors hover:text-ink hover:decoration-accent"
+						class="text-sm font-medium text-ink-2 transition-colors hover:text-ink"
 						aria-label={m.notification_mark_all_read_aria()}
 					>
 						{m.notification_mark_all_read()}

frontend/src/routes/profile/+page.svelte

@@ -104,7 +104,7 @@ const hasEmail = $derived(!!data.user?.email);
 		<div class="mt-4 border-t border-line pt-4">
 			<a
 				href="/notifications"
-				class="text-sm font-medium text-ink-2 underline decoration-accent/60 transition-colors hover:text-ink hover:decoration-accent"
+				class="text-sm font-medium text-ink-2 transition-colors hover:text-ink"
 			>
 				{m.notification_history_view_link()}
 			</a>