Add eslint for typescript with React

Eslint will be used with github actions to perform check on every
push and pr.

Author: NorbertLoh

frontend/peerprep/app/routes/home.tsx

@@ -1,7 +1,6 @@
-import type { Route } from "./+types/home";
 import { Welcome } from "../welcome/welcome";
 
-export function meta({}: Route.MetaArgs) {
+export function meta() {
   return [
     { title: "New React Router App" },
     { name: "description", content: "Welcome to React Router!" },

frontend/peerprep/eslint.config.js

@@ -0,0 +1,32 @@
+// Setup guide from : https://eslint-react.xyz/docs/getting-started/typescript
+
+// @ts-check
+import eslintJs from "@eslint/js";
+import eslintReact from "@eslint-react/eslint-plugin";
+import tseslint from "typescript-eslint";
+export default tseslint.config({
+  files: ["**/*.ts", "**/*.tsx"],
+  // Extend recommended rule sets from:
+  // 1. ESLint JS's recommended rules
+  // 2. TypeScript ESLint recommended rules
+  // 3. ESLint React's recommended-typescript rules
+  extends: [
+    eslintJs.configs.recommended,
+    tseslint.configs.recommended,
+    eslintReact.configs["recommended-typescript"],
+  ],
+  // Configure language/parsing options
+  languageOptions: {
+    // Use TypeScript ESLint parser for TypeScript files
+    parser: tseslint.parser,
+    parserOptions: {
+      // Enable project service for better TypeScript integration
+      projectService: true,
+      tsconfigRootDir: import.meta.dirname,
+    },
+  },
+  // Custom rule overrides (modify rule levels or disable rules)
+  rules: {
+    "@eslint-react/no-missing-key": "warn",
+  },
+});