refactor: extract language toggle into reusable components

Create Toggle and LanguageToggle components to reduce code duplication
and enable shared state across pages.

- Add Toggle.svelte: Generic iOS-style toggle with customizable accent color
- Add LanguageToggle.svelte: Language-specific toggle with localStorage persistence
- Refactor rosary page to use new toggle components
- Add language toggle to gebete page
- Toggle state persists across both pages via localStorage
- Reduce min-height of Ave Maria decades in monolingual mode (50vh → 30vh)

src/lib/components/LanguageToggle.svelte

@@ -0,0 +1,39 @@
+<script>
+	import { onMount } from 'svelte';
+	import { getLanguageContext } from '$lib/contexts/languageContext.js';
+	import Toggle from './Toggle.svelte';
+
+	// Get the language context (must be created by parent page)
+	const { showLatin } = getLanguageContext();
+
+	// Local state for the checkbox
+	let showBilingual = true;
+
+	// Flag to prevent saving before we've loaded from localStorage
+	let hasLoadedFromStorage = false;
+
+	// Sync checkbox with context
+	$: $showLatin = showBilingual;
+
+	// Save to localStorage whenever it changes (but only after initial load)
+	$: if (typeof localStorage !== 'undefined' && hasLoadedFromStorage) {
+		localStorage.setItem('rosary_showBilingual', showBilingual.toString());
+	}
+
+	onMount(() => {
+		// Load from localStorage
+		const saved = localStorage.getItem('rosary_showBilingual');
+		if (saved !== null) {
+			showBilingual = saved === 'true';
+		}
+
+		// Now allow saving
+		hasLoadedFromStorage = true;
+	});
+</script>
+
+<Toggle
+	bind:checked={showBilingual}
+	label="Lateinisch und Deutsch anzeigen"
+	accentColor="var(--nord14)"
+/>