🌐 feat: add i18n support to 6 web apps

Add internationalization (DE + EN) to previously missing apps:
- todo: task management translations
- skilltree: skill/XP system translations
- nutriphi: nutrition tracking translations
- planta: plant care translations
- questions: research app translations
- matrix: chat client translations (layout integration)

Each app includes:
- svelte-i18n setup with SSR support
- localStorage persistence ({app}_locale pattern)
- i18n loading state in +layout.svelte
- German (default) and English translations

Updated CONSISTENCY_REPORT.md to mark i18n task as complete.

Also includes:
- mana-tts service placeholder files

apps/matrix/apps/web/src/routes/+layout.svelte

@@ -1,7 +1,9 @@
 <script lang="ts">
 	import '../app.css';
+	import '$lib/i18n';
 	import { onMount } from 'svelte';
 	import type { Snippet } from 'svelte';
+	import { isLoading as i18nLoading, _ as t } from 'svelte-i18n';
 	import { theme } from '$lib/stores/theme';
 	import { ToastContainer } from '@manacore/shared-ui';
 
@@ -18,7 +20,7 @@
 </script>
 
 <svelte:head>
-	<title>Mana Matrix</title>
+	<title>{$t('app.name')}</title>
 	<meta name="description" content="Self-hosted Matrix chat client" />
 </svelte:head>