feat: --minimal option

Closes vuejs#112
Closes vuejs#300

The minimal template is a cut-down version of the default template;
therefore, the `--minimal` flag is mutually exclusive with all other flags.
I chose not to include it in the prompts because it's a very specific
use case, and it's not a good idea to clutter the CLI with too many
options that are not commonly used.

I didn't design it as an add-on because the logic would be too complex,
and the use case would be even more niche.

index.ts

@@ -72,6 +72,7 @@ async function init() {
   const cwd = process.cwd()
   // possible options:
   // --default
+  // --minimal
   // --typescript / --ts
   // --jsx
   // --router / --vue-router
@@ -107,6 +108,7 @@ async function init() {
   const isFeatureFlagsUsed =
     typeof (
       argv.default ??
+      argv.minimal ??
       (argv.ts || argv.typescript) ??
       argv.jsx ??
       (argv.router || argv['vue-router']) ??
@@ -563,6 +565,31 @@ async function init() {
     )
   }
 
+  if (argv.minimal) {
+    // Only keep `src/App.vue` and `src/main.js` inside the `src` folder
+    postOrderDirectoryTraverse(
+      path.resolve(root, 'src'),
+      (dir) => {
+        if (path.basename(dir) === 'src') {
+          return
+        }
+        fs.rmdirSync(dir)
+      },
+      (filepath) => {
+        if (!['App.vue', 'main.js'].includes(path.basename(filepath))) fs.unlinkSync(filepath)
+      },
+    )
+    // Replace the content in `src/App.vue` with a minimal template
+    fs.writeFileSync(
+      path.resolve(root, 'src/App.vue'),
+      '<script setup>\n</script>\n\n<template>\n  <h1>Hello World</h1>\n</template>\n\n<style scoped>\n</style>\n',
+    )
+    // Remove CSS import in `src/main.js`
+    const srcMainJsPath = path.resolve(root, 'src/main.js')
+    const srcMainJsContent = fs.readFileSync(srcMainJsPath, 'utf8')
+    fs.writeFileSync(srcMainJsPath, srcMainJsContent.replace("import './assets/main.css'\n\n", ''))
+  }
+
   // Instructions:
   // Supported package managers: pnpm > yarn > bun > npm
   const userAgent = process.env.npm_config_user_agent ?? ''