fix: pass app version via server load instead of Vite define

The Svelte 5 SSR compiler was optimizing away the __APP_VERSION__
constant set via Vite's define, causing the version to be missing
from the production footer. Use a +layout.server.ts load function
to pass the version from package.json instead.

Also bumps version to 0.1.6.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/app.d.ts

@@ -1,8 +1,6 @@
 // See https://svelte.dev/docs/kit/types#app.d.ts
 // for information about these interfaces
 declare global {
-	const __APP_VERSION__: string;
-
 	namespace App {
 		// interface Error {}
 		// interface Locals {}

src/routes/+layout.server.ts

@@ -0,0 +1,5 @@
+import { version } from '../../package.json';
+
+export function load() {
+	return { appVersion: version };
+}

src/routes/+layout.svelte

@@ -6,9 +6,7 @@
 	import { loadNotes } from '$lib/stores/notes.js';
 	import { onMount } from 'svelte';
 
-	const appVersion = __APP_VERSION__;
-
-	let { children } = $props();
+	let { data, children } = $props();
 	let sidebarOpen = $state(false);
 
 	onMount(() => {
@@ -27,7 +25,7 @@
 	</main>
 
 	<footer class="pb-4 pt-8 text-center text-xs text-gray-400 lg:ml-64">
-		Crumbs by Bretzel v{appVersion} &mdash; made with 🥨 in Strasbourg
+		Crumbs by Bretzel v{data.appVersion} &mdash; made with 🥨 in Strasbourg
 	</footer>
 
 	<Toast />