feat(items): implement initial item management system

This commit introduces the foundational structure and core features for the item management application.

Key features implemented:
- **Item Listing:** A main page displaying all items in a searchable UTable.
- **Item Creation:** An "Add Item" modal with a UForm for input and validation using Zod.
- **State Management:** A `useItemsStore` composable built with `@vueuse/core`'s `useLocalStorage` to persist item data
in the browser.
- **UI Framework:** Integrated Nuxt UI for components like tables, modals, forms, and the overall layout.
- **Application Shell:** Established a default layout with a header, navigation menu, and placeholders for Export and
History pages.
- **Project Setup:** Configured pnpm workspace, Tailwind CSS, and VSCode editor settings for an improved development
experience.

nuxt.config.ts

@@ -2,5 +2,6 @@
 export default defineNuxtConfig({
   compatibilityDate: '2025-07-15',
   devtools: { enabled: true },
+  css: ['~/assets/css/main.css'],
   modules: ['@nuxt/ui']
 })