Label stock ticker % change with its interval

The change % is since the previous trading day's close (Yahoo's
own definition, same as any standard quote), but nothing on screen
said so. Sidebar widget now shows a "today" label next to the
Stocks header; admin Stocks tab gets an explanatory hint above the
list.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014c1L8ghNBFjfiH64UMViP8

frontend/src/lib/components/admin/StocksTab.svelte

@@ -44,6 +44,7 @@
 	<span class="count">{tickers.length} tickers</span>
 	<button class="add-btn" onclick={() => (showAdd = !showAdd)}>+ New ticker</button>
 </div>
+<p class="hint" style="margin: -6px 0 12px;">Price and % change are today's — since the previous trading day's close.</p>
 
 {#if showAdd}
 	<div class="add-panel">

frontend/src/lib/components/sidebar/StocksWidget.svelte

@@ -5,7 +5,10 @@
 </script>
 
 <div class="widget">
+	<div class="head">
 		<span class="title">Stocks</span>
+		{#if stocks.length > 0}<span class="interval">today</span>{/if}
+	</div>
 	{#if stocks.length > 0}
 		<div class="list">
 			{#each stocks as stock (stock.id)}
@@ -35,11 +38,20 @@
 		border-radius: 12px;
 		padding: 14px;
 	}
+	.head {
+		display: flex;
+		align-items: baseline;
+		justify-content: space-between;
+	}
 	.title {
 		font-size: 12px;
 		font-weight: 500;
 		color: var(--text-muted);
 	}
+	.interval {
+		font-size: 10px;
+		color: var(--text-muted);
+	}
 	.list {
 		display: flex;
 		flex-direction: column;