Add rich text editor and enhanced date picker to event dialogs

Replace basic textarea with VuetifyTiptap rich text editor for event descriptions, supporting formatting options like bold, italic, headings, and lists. Replace native datetime inputs with VueDatePicker components featuring timezone support (Monaco/UTC) and improved UX. Update dependencies and add necessary plugins to support the new components.

plugins/vue-datepicker.client.ts

@@ -0,0 +1,6 @@
+import VueDatePicker from '@vuepic/vue-datepicker'
+import '@vuepic/vue-datepicker/dist/main.css'
+
+export default defineNuxtPlugin((nuxtApp) => {
+  nuxtApp.vueApp.component('VueDatePicker', VueDatePicker)
+})