fix: downgrade ESLint to v8 for Next.js compatibility

- Downgrade ESLint from v9 to v8.57.0 (required by eslint-config-next)
- Replace eslint.config.js with .eslintrc.json
- Remove incompatible ESLint plugins
- Use standard Next.js ESLint configuration

This resolves the peer dependency conflict where eslint-config-next
requires ESLint 7 or 8, not 9.

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

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

.eslintrc.json

@@ -0,0 +1,3 @@
+{
+  "extends": ["next/core-web-vitals"]
+}

eslint.config.js

@@ -1,18 +0,0 @@
-const { defineConfig, globalIgnores } = require("eslint/config");
-const nextVitals = require("eslint-config-next/core-web-vitals");
-const nextTs = require("eslint-config-next/typescript");
-
-const eslintConfig = defineConfig([
-  ...nextVitals,
-  ...nextTs,
-  // Override default ignores of eslint-config-next.
-  globalIgnores([
-    // Default ignores of eslint-config-next:
-    ".next/**",
-    "out/**",
-    "build/**",
-    "next-env.d.ts",
-  ]),
-]);
-
-module.exports = eslintConfig;

eslint.config.mjs

@@ -1,18 +0,0 @@
-import { defineConfig, globalIgnores } from "eslint/config";
-import nextVitals from "eslint-config-next/core-web-vitals";
-import nextTs from "eslint-config-next/typescript";
-
-const eslintConfig = defineConfig([
-  ...nextVitals,
-  ...nextTs,
-  // Override default ignores of eslint-config-next.
-  globalIgnores([
-    // Default ignores of eslint-config-next:
-    ".next/**",
-    "out/**",
-    "build/**",
-    "next-env.d.ts",
-  ]),
-]);
-
-export default eslintConfig;

eslint.config.mts

@@ -1,11 +0,0 @@
-import js from "@eslint/js";
-import globals from "globals";
-import tseslint from "typescript-eslint";
-import pluginReact from "eslint-plugin-react";
-import { defineConfig } from "eslint/config";
-
-export default defineConfig([
-  { files: ["**/*.{js,mjs,cjs,ts,mts,cts,jsx,tsx}"], plugins: { js }, extends: ["js/recommended"], languageOptions: { globals: globals.browser } },
-  tseslint.configs.recommended,
-  pluginReact.configs.flat.recommended,
-]);

package.json

@@ -26,18 +26,14 @@
     "zod": "^4.1.12"
   },
   "devDependencies": {
-    "@eslint/js": "^9.39.1",
     "@types/node": "24.9.2",
     "@types/react": "19.2.2",
     "autoprefixer": "^10.4.21",
-    "eslint": "^9.39.1",
+    "eslint": "^8.57.0",
     "eslint-config-next": "14.2.4",
-    "eslint-plugin-react": "^7.37.5",
-    "globals": "^16.5.0",
     "jiti": "^2.6.1",
     "postcss": "^8.5.6",
     "tailwindcss": "^3.4.13",
-    "typescript": "5.9.3",
-    "typescript-eslint": "^8.46.3"
+    "typescript": "5.9.3"
   }
 }