feat(project): scaffold Vue 3 + Vite markdown editor

Add initial project structure including:
- .gitignore and VSCode settings
- Vite configuration and package.json with Vue 3 dependencies
- Basic HTML entry point and README update
- Core source files: App.vue, main.js, style.css
- Markdown editor component with plugin system and related types
- Sample HelloWorld component, router, and Pinia store
- Assets and SVG icons

This commit establishes the foundation for the Vue 3 application.

README.md

@@ -1,2 +1,5 @@
-# llm-in-text
+# Vue 3 + Vite
 
+This template should help get you started developing with Vue 3 in Vite. The template uses Vue 3 `<script setup>` SFCs, check out the [script setup docs](https://v3.vuejs.org/api/sfc-script-setup.html#sfc-script-setup) to learn more.
+
+Learn more about IDE Support for Vue in the [Vue Docs Scaling up Guide](https://vuejs.org/guide/scaling-up/tooling.html#ide-support).