EsLint v9 (#154)

* Upgrade ESLint and related configurations to version 9

- Update ESLint to version 9.19.0
- Migrate ESLint configurations to flat config format
- Remove deprecated ESLint config files
- Update package dependencies and configurations
- Simplify ESLint setup across packages
- Remove unnecessary ESLint config blocks from package.json files
- Improved CI caching with Turborepo tasks
- Removed duplicate styles

apps/web/package.json

@@ -10,7 +10,8 @@
     "build:test": "NODE_ENV=test pnpm with-env:test next build",
     "clean": "git clean -xdf .next .turbo node_modules",
     "dev": "pnpm with-env next dev --turbo | pino-pretty -c",
-    "lint": "next lint && eslint .",
+    "lint": "eslint .",
+    "lint:fix": "next lint --fix",
     "format": "prettier --check \"**/*.{js,cjs,mjs,ts,tsx,md,json}\"",
     "start": "pnpm with-env next start",
     "start:test": "NODE_ENV=test pnpm with-env:test next start",
@@ -75,17 +76,16 @@
   "devDependencies": {
     "@kit/eslint-config": "workspace:*",
     "@kit/prettier-config": "workspace:*",
-    "@kit/tailwind-config": "workspace:*",
     "@kit/tsconfig": "workspace:*",
     "@next/bundle-analyzer": "15.1.6",
+    "@tailwindcss/postcss": "^4.0.4",
     "@types/mdx": "^2.0.13",
     "@types/node": "^22.13.0",
     "@types/react": "19.0.8",
     "@types/react-dom": "19.0.3",
     "autoprefixer": "^10.4.20",
-    "babel-plugin-react-compiler": "19.0.0-beta-e552027-20250112",
+    "babel-plugin-react-compiler": "beta",
     "dotenv-cli": "^8.0.0",
-    "eslint": "^8.57.0",
     "import-in-the-middle": "1.12.0",
     "pino-pretty": "^13.0.0",
     "prettier": "^3.4.2",