feat: add sound effects, improved stroke recognition, instant locale switching with scramble text animation

- Add SoundManager with Web Audio API synthesized sounds (stroke error, drawing complete, session complete)
- Add sound effects toggle in settings (persisted via localStorage)
- Improve stroke recognition: curvature similarity, max point deviation, stroke length ratio checks
- Loosen thresholds for long strokes and first-stroke positioning
- Implement instant locale switching (no save required)
- Add ScrambleText component with character-by-character morphing animation
- Apply ScrambleText globally across all views, widgets, and dialogs
- Add i18n keys for sound effects settings (EN/DE/JA)

client/src/components/dashboard/WidgetForecast.vue

@@ -7,7 +7,7 @@
       div(v-for="(count, hour) in forecast" :key="hour")
         .d-flex.justify-space-between.align-center.mb-2.py-2.border-b-subtle(v-if="count > 0")
           span.text-body-2.text-grey-lighten-1
-            | {{ hour === 0 ? $t('stats.availableNow') : $t('stats.inHours', { n: hour }, hour) }}
+            ScrambleText(:text="hour === 0 ? $t('stats.availableNow') : $t('stats.inHours', { n: hour }, hour)")
 
           v-chip.font-weight-bold.text-primary(
             size="small"
@@ -15,7 +15,7 @@
           ) {{ count }}
 
     .fill-height.d-flex.align-center.justify-center.text-grey.text-center.pa-4(v-else)
-      | {{ $t('stats.noIncoming') }}
+      ScrambleText(:text="$t('stats.noIncoming')")
 </template>
 
 <script setup>
@@ -24,7 +24,7 @@ import { computed } from 'vue';
 import DashboardWidget from './DashboardWidget.vue';
 
 const props = defineProps({
-  forecast: { type: Object, default: () => ({}) },
+  forecast: { type: Array, default: () => [] },
 });
 
 const hasUpcoming = computed(() => props.forecast && props.forecast.some((c) => c > 0));