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

packages/billing/gateway/package.json

@@ -24,7 +24,6 @@
     "@kit/shared": "workspace:*",
     "@kit/stripe": "workspace:*",
     "@kit/supabase": "workspace:*",
-    "@kit/tailwind-config": "workspace:*",
     "@kit/tsconfig": "workspace:*",
     "@kit/ui": "workspace:*",
     "@supabase/supabase-js": "2.48.1",
@@ -37,13 +36,6 @@
     "react-i18next": "^15.4.0",
     "zod": "^3.24.1"
   },
-  "eslintConfig": {
-    "root": true,
-    "extends": [
-      "@kit/eslint-config/base",
-      "@kit/eslint-config/react"
-    ]
-  },
   "typesVersions": {
     "*": {
       "*": [
@@ -51,4 +43,4 @@
       ]
     }
   }
-}
+}