chore(frontend): prettier formating

- add a `format` script to run prettier.
- change the line width from 120 to 100.
- ignore the generated API client.

frontend/.prettierignore

@@ -0,0 +1,2 @@
+# ignore auto-generated code
+src/lib/api-client

frontend/.prettierrc.js

@@ -2,6 +2,6 @@ module.exports = {
   semi: true,
   trailingComma: 'all',
   singleQuote: true,
-  printWidth: 120,
+  printWidth: 100,
   tabWidth: 2,
 };

frontend/package.json

@@ -71,6 +71,7 @@
     "test": "react-scripts test",
     "eject": "react-scripts eject",
     "lint": "eslint src/**/*.{js,jsx}",
+    "format": "prettier --write .",
     "generate-client": "openapi --input http://localhost:8888/openapi.json --output ./src/lib/api-client --client fetch --name ApiClient --useOptions"
   },
   "browserslist": [