feat(fase-16): add Spinner component + unit tests

Fase 16.1 — reusable inline loading indicator. SVG circle with
stroke-dasharray + Tailwind animate-spin (respects motion-reduce).
Sizes: sm=16, md=24, lg=40. Inherits currentColor so it plays nicely
with the Fase 9 theme tokens. Wrapper has role=status + aria-live=polite
and an sr-only m.loading() label (no new Paraglide strings).

vitest.config: resolve.conditions=['browser'] + inline svelte so the
Svelte 5 mount() API resolves to index-client.js instead of the server
entry. Without it the new Spinner.test throws lifecycle_function_unavailable.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

apps/web/src/lib/components/Spinner.svelte

@@ -0,0 +1,34 @@
+<script lang="ts">
+	import * as m from '$lib/paraglide/messages';
+
+	interface Props {
+		size?: 'sm' | 'md' | 'lg';
+		class?: string;
+	}
+	let { size = 'md', class: extra = '' }: Props = $props();
+
+	const px = $derived(size === 'sm' ? 16 : size === 'lg' ? 40 : 24);
+</script>
+
+<div role="status" aria-live="polite" class={extra}>
+	<svg
+		data-testid="spinner"
+		width={px}
+		height={px}
+		viewBox="0 0 24 24"
+		fill="none"
+		class="animate-spin motion-reduce:animate-none"
+	>
+		<circle
+			cx="12"
+			cy="12"
+			r="9"
+			stroke="currentColor"
+			stroke-width="2.5"
+			stroke-linecap="round"
+			stroke-dasharray="42 14"
+			opacity="0.75"
+		/>
+	</svg>
+	<span class="sr-only">{m.loading()}</span>
+</div>