project: add prettier

prettier.config.js

@@ -0,0 +1,28 @@
+//  @ts-check
+
+/** @type {import('prettier').Config} */
+const config = {
+  arrowParens: 'always',
+  bracketSameLine: false,
+  objectWrap: 'preserve',
+  bracketSpacing: true,
+  semi: true,
+  experimentalOperatorPosition: 'end',
+  experimentalTernaries: true,
+  singleQuote: true,
+  jsxSingleQuote: true,
+  quoteProps: 'as-needed',
+  trailingComma: 'all',
+  singleAttributePerLine: false,
+  htmlWhitespaceSensitivity: 'css',
+  vueIndentScriptAndStyle: false,
+  proseWrap: 'preserve',
+  insertPragma: false,
+  printWidth: 100,
+  requirePragma: false,
+  tabWidth: 2,
+  useTabs: false,
+  embeddedLanguageFormatting: 'auto',
+};
+
+export default config;