Modernize the Linting Setup

Problem/Feature Description

The payments-api project has been using the standard package for linting since it was created three years ago. The team is now hitting friction: standard doesn't support ESLint v9, the ecosystem of plugins they want to adopt uses flat config, and onboarding new developers is getting messy because some editors support the old vscode-standard extension while others use the ESLint extension.

The engineering lead wants to migrate the project to a modern ESLint setup that preserves the Standard-like rules the team is comfortable with, while moving to the current ESLint v9 flat config system. The migration should not change which lint rules are enforced — it's purely a tooling upgrade, not a rule overhaul.

Your task is to migrate the project from its current linting setup to a modern equivalent, update all scripts and configuration, and produce a brief migration notes file documenting what was changed and why each step was taken separately.

Output Specification

Produce the following files:

• package.json — updated (dependencies and scripts modernized)
• eslint.config.js — the new ESLint flat config
• migration-notes.md — a short document listing what was changed, in what order, and the reasoning for separating any steps
• migrate.sh — a shell script that performs the migration steps from start to finish

Input Files

The following files are provided as inputs. Extract them before beginning.

=============== FILE: package.json =============== { "name": "payments-api", "version": "2.3.1", "description": "Payments processing API", "main": "index.js", "type": "module", "scripts": { "test": "node --test", "lint": "standard", "lint:fix": "standard --fix" }, "standard": { "ignore": [ "dist/**" ] }, "devDependencies": { "standard": "^17.1.0" } }

=============== FILE: index.js =============== import { createServer } from 'http'

export function startServer (port) { const server = createServer((req, res) => { res.writeHead(200) res.end('OK') }) server.listen(port) return server }

=============== FILE: .gitignore =============== node_modules/ dist/ .env