fix(dashboard): count Recent workloads by source_kind, not raw rows

The Recent-workloads badge and empty-state guard used workloads.length
(which includes legacy kind:site rows with empty source_kind) while the
list renders pluginWorkloads (source_kind != ''). With one legacy row and
no real workloads the badge showed "1" over an empty list and the empty
state never appeared. Both now use pluginWorkloads, matching the list and
the headline Total count.

web/src/routes/+page.svelte

@@ -186,7 +186,7 @@
 	<CollapsibleSection
 		id="dashboard-workloads"
 		title={$t('dashboard.recentWorkloads')}
-		badge={!loading && workloads.length > 0 ? String(workloads.length) : ''}
+		badge={!loading && pluginWorkloads.length > 0 ? String(pluginWorkloads.length) : ''}
 	>
 		{#if loading}
 			<div class="grid grid-cols-1 gap-4 sm:grid-cols-2 lg:grid-cols-3">
@@ -205,7 +205,7 @@
 					{$t('dashboard.retry')}
 				</button>
 			</div>
-		{:else if workloads.length === 0}
+		{:else if pluginWorkloads.length === 0}
 			<EmptyState
 				title={$t('dashboard.noWorkloads')}
 				description={$t('dashboard.noWorkloadsDesc')}