feat: complete Svelte 5 migration across entire application

Migrated all components and routes from Svelte 4 to Svelte 5 syntax:

- Converted export let → $props() with generic type syntax
- Replaced createEventDispatcher → callback props
- Migrated $: reactive statements → $derived() and $effect()
- Updated two-way bindings with $bindable()
- Fixed TypeScript syntax: added lang="ts" to script tags
- Converted inline type annotations to generic parameter syntax

- Updated deprecated event directives to Svelte 5 syntax:
  - on:click → onclick
  - on:submit → onsubmit
  - on:change → onchange

- Converted deprecated <slot> elements → {@render children()}
- Updated slot props to Snippet types
- Fixed season/icon selector components with {#snippet} blocks

- Fixed non-reactive state by converting let → $state()
- Fixed infinite loop in EnhancedBalance by converting $effect → $derived
- Fixed Chart.js integration by converting $state proxies to plain arrays
- Updated cospend dashboard and payment pages with proper reactivity

- Migrated 20+ route files from export let data → $props()
- Fixed TypeScript type annotations in page components
- Updated reactive statements in error and cospend routes

- Removed invalid onchange attribute from Toggle component
- Fixed modal ID isolation in CreateIngredientList/CreateStepList
- Fixed dark mode button visibility in TranslationApproval
- Build now succeeds with zero deprecation warnings

All functionality tested and working. No breaking changes to user experience.

src/lib/components/prayers/Prayer.svelte

@@ -1,7 +1,8 @@
-<script>
+<script lang="ts">
+	import type { Snippet } from 'svelte';
 	import { getLanguageContext } from '$lib/contexts/languageContext.js';
 
-	export let latinPrimary = true; // Controls which language is shown prominently
+	let { latinPrimary = true, children } = $props<{ latinPrimary?: boolean, children?: Snippet }>();
 
 	// Get context if available (graceful fallback for standalone usage)
 	let showLatinStore;
@@ -12,7 +13,7 @@
 		showLatinStore = null;
 	}
 
-	$: showLatin = showLatinStore ? $showLatinStore : true;
+	let showLatin = $derived(showLatinStore ? $showLatinStore : true);
 </script>
 
 <style>
@@ -123,5 +124,5 @@
 </style>
 
 <div class="prayer-wrapper" class:german-primary={!latinPrimary} class:monolingual={!showLatin}>
-	<slot></slot>
+	{@render children?.()}
 </div>