npm run lint is broken: eslint is not in devDependencies and no config exists

## Problem

`package.json` defines a lint script:

```json
"lint": "eslint src/ test/"
```

but:

1. `eslint` is not listed in `devDependencies` (the object is empty).
2. There is no ESLint configuration file in the repo (`.eslintrc*`, `eslint.config.js`, or an `eslintConfig` key in `package.json`).

As a result, a fresh `npm ci && npm run lint` fails immediately with `eslint: command not found`, and even if ESLint were installed it would error out on a missing config.

## Repro

```bash
git clone https://github.com/addyosmani/agentic-seo.git
cd agentic-seo
npm ci
npm run lint
# sh: eslint: command not found
```

## Possible fixes

There are two reasonable directions, and I'd like to know which one you prefer before opening a PR:

1. **Drop linting**: remove the `lint` script from `package.json`. Minimal change, reflects current reality.
2. **Wire up linting properly**: add `eslint` to `devDependencies`, add a minimal flat config (`eslint.config.js`) tuned to the codebase (ESM, Node >=18), and fix any findings it surfaces. Slightly larger change but gives the repo real lint coverage.

Happy to contribute either fix as a follow-up PR — just let me know which direction you'd prefer.