feat: initialise Vue 3 SPA template

- Add Tailwind CSS v4 with light/dark theme support
- Add layout system (default, sidebar, blank)
- Add mock authentication with Pinia store and route guards
- Add error pages (404, 500) and example views
- Add Vitest with 10 example tests across stores
- Configure Prettier formatting and ESLint linting

vite.config.ts

@@ -0,0 +1,20 @@
+import { fileURLToPath, URL } from 'node:url'
+
+import { defineConfig } from 'vite'
+import vue from '@vitejs/plugin-vue'
+import vueDevTools from 'vite-plugin-vue-devtools'
+import tailwindcss from '@tailwindcss/vite'
+
+// https://vite.dev/config/
+export default defineConfig({
+  plugins: [
+    vue(),
+    vueDevTools(),
+    tailwindcss(),
+  ],
+  resolve: {
+    alias: {
+      '@': fileURLToPath(new URL('./src', import.meta.url))
+    },
+  },
+})