feat!: rewrite frontend in Vue 3 with Pinia, DaisyUI, vite-plugin-pwa

Migrates every component from class-based vue-property-decorator to
<script setup> + Composition API. Replaces Vuex 3 + vuex-class with a
single Pinia store (persisted via pinia-plugin-persistedstate). Swaps
Bulma + bulma-{checkradio,switch,pricingtable} for DaisyUI 5 utilities
on Tailwind 4. Replaces register-service-worker with vite-plugin-pwa
(workbox, skipWaiting/clientsClaim preserved).

Plugins replaced:
- vue-class-component / vue-property-decorator -> <script setup>
- vuex / vuex-class / vuex-persist -> pinia + persistedstate
- vue-i18n 8 -> vue-i18n 11 (composition mode, legacy: false)
- vue-click-outside -> @vueuse/core onClickOutside
- @xkeshi/vue-qrcode -> qrcode.vue
- vue-currency-input 1 -> vue-currency-input 3 (composable wrapper)
- bus-event (Vue instance) -> mitt
- Vue filters -> plain functions imported per component

BREAKING: drops Stripe / pricing entirely (Payment, PricingTable,
/pricing route, vue-stripe-checkout, bulma-pricingtable).

Clears unused Cypress and Jest test scaffolding; leaves a Vitest
harness behind for future tests.

src/i18n/index.ts

@@ -0,0 +1,11 @@
+import { createI18n } from 'vue-i18n'
+import messages from '@/messages'
+
+const i18n = createI18n({
+  legacy: false,
+  locale: 'fr',
+  fallbackLocale: 'en',
+  messages
+})
+
+export default i18n