fix: show item ref (e.g. TASK-5) in breadcrumb instead of full title (#7)

Breadcrumb now reads "Home / Tasks / TASK-5" instead of
"Home / Tasks / Fix the OAuth redirect bug" — much cleaner navigation.
Falls back to title if no item ref exists.

web/src/routes/[workspace]/[collection]/[slug]/+page.svelte

@@ -273,7 +273,7 @@
 			<span class="sep">/</span>
 			<a href="/{wsSlug}/{collSlug}">{collection.icon} {collection.name}</a>
 			<span class="sep">/</span>
-			<span class="current">{item.title}</span>
+			<span class="current">{formatItemRef(item) || item.title}</span>
 		</nav>
 
 		<!-- Title -->