feat: migrate ESLint to v9 flat config

- Replace .eslintrc.json with eslint.config.mjs
- Simplify configuration using @antfu/eslint-config
- Add necessary ESLint plugin dependencies
- Disable overly strict style rules
- Set package.json type to module for ESM support
- Fix ESLint disable comment format

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

app/components/chat/loading-anim/index.tsx

@@ -3,7 +3,7 @@ import type { FC } from 'react'
 import React from 'react'
 import s from './style.module.css'
 
-export type ILoaidingAnimProps = {
+export interface ILoaidingAnimProps {
   type: 'text' | 'avatar'
 }