style(#145): bump dashboard widget content links to text-lg

Box content links (document titles, actor names) raised from text-sm to
text-lg for improved readability and touch target size. "Show all" stays
at text-sm to maintain hierarchy — box links are the primary action.

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

frontend/src/lib/components/DashboardMentions.svelte

@@ -31,7 +31,7 @@ let { mentions }: Props = $props();
 						href={mention.annotationId
 							? `/documents/${mention.documentId}?commentId=${mention.referenceId}&annotationId=${mention.annotationId}`
 							: `/documents/${mention.documentId}?commentId=${mention.referenceId}`}
-						class="font-serif text-sm text-ink hover:text-ink-2"
+						class="font-serif text-lg text-ink hover:text-ink-2"
 					>
 						{mention.actorName ?? ''}
 						{#if mention.type === 'MENTION'}<span class="ml-1 font-sans text-xs text-gray-400"
@@ -41,7 +41,7 @@ let { mentions }: Props = $props();
 							>{/if}
 					</a>
 				{:else}
-					<span class="font-serif text-sm text-ink">{mention.actorName ?? ''}</span>
+					<span class="font-serif text-lg text-ink">{mention.actorName ?? ''}</span>
 				{/if}
 			</div>
 		{/each}