web: unify empty + loading states behind EmptyState/InlineLoader

Replaces ad-hoc "Loading…" text and bare empty messages with two
shared feedback primitives that carry subtle lucide icons, consistent
muted-foreground/destructive tones, and a11y signaling (role=status,
aria-busy, role=alert on destructive empties). Loading copy gains
context ("Loading photos/folders/heaps/metadata…") and the right-
sidebar idle state moves from a "ⓘ" glyph to a MousePointerClick
icon. SkeletonGrid stays as the initial-grid loader.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

web/src/lib/components/feedback/InlineLoader.svelte

@@ -0,0 +1,39 @@
+<!--
+	Tiny "Loading…" indicator: spinner + label. Use this for in-flight queries
+	in sidebars, popovers, and right rails. For the initial photo-grid load,
+	use SkeletonGrid instead (layout-preserving).
+-->
+<script lang="ts">
+	import { Loader2 } from 'lucide-svelte';
+
+	interface Props {
+		label?: string;
+		size?: 'sm' | 'default';
+		align?: 'left' | 'center';
+		srOnly?: boolean;
+		polite?: boolean;
+	}
+
+	let {
+		label = 'Loading…',
+		size = 'default',
+		align = 'left',
+		srOnly = false,
+		polite = true
+	}: Props = $props();
+
+	const textSize = $derived(size === 'sm' ? 'text-[11px]' : 'text-xs');
+	const iconSize = $derived(size === 'sm' ? 'h-3 w-3' : 'h-3.5 w-3.5');
+	const padding = $derived(size === 'sm' ? 'px-3 py-2' : 'px-3 py-2');
+	const justify = $derived(align === 'center' ? 'justify-center' : 'justify-start');
+</script>
+
+<p
+	role="status"
+	aria-busy="true"
+	aria-live={polite ? 'polite' : 'off'}
+	class="flex items-center gap-1.5 {padding} {textSize} {justify} text-muted-foreground"
+>
+	<Loader2 class="{iconSize} animate-spin" aria-hidden="true" />
+	<span class={srOnly ? 'sr-only' : ''}>{label}</span>
+</p>