[QOTD-4] Configure ESLint with @typescript-eslint recommended rules

Add eslint.config.mjs (flat config) using @typescript-eslint/eslint-plugin
flat/recommended rules. Add npm run lint script (exits 0 on current codebase).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

CLAUDE.md

@@ -42,8 +42,10 @@ quote-of-the-day-api/
 ├── src/               # TypeScript source
 │   └── placeholder.test.ts  # harness smoke test
 ├── dist/              # compiled output (git-ignored)
+├── eslint.config.mjs  # ESLint flat config (@typescript-eslint recommended)
 ├── package.json
 ├── package-lock.json
+├── tsconfig.json
 ├── .gitignore
 ├── README.md          # Project overview (currently a stub)
 └── CLAUDE.md          # This file
@@ -61,9 +63,7 @@ quote-of-the-day-api/
 
 ## Code Style
 
-> Update this section once a linter/formatter config is committed (`.eslintrc`, etc.).
+- **TypeScript**: `strict: true`, `target: "ES2020"` in `tsconfig.json`
-
+- **Linting**: ESLint 10 flat config (`eslint.config.mjs`) using `@typescript-eslint/eslint-plugin` `flat/recommended` rules; run `npm run lint` — must exit 0
-- **TypeScript**: `strict: true`, `target: "ES2020"` recommended in `tsconfig.json`
-- **Linting**: ESLint with `@typescript-eslint` rules; `npm run lint` must exit cleanly
 - Follow the conventions of the chosen language's ecosystem formatter (e.g., Prettier for JS/TS).
 - Keep controllers thin; put business logic in service or domain layers.

eslint.config.mjs

@@ -0,0 +1,12 @@
+import tsPlugin from '@typescript-eslint/eslint-plugin';
+import tsParser from '@typescript-eslint/parser';
+
+export default [
+  ...tsPlugin.configs['flat/recommended'],
+  {
+    files: ['**/*.ts'],
+    languageOptions: {
+      parser: tsParser,
+    },
+  },
+];

package.json

@@ -6,6 +6,7 @@
   "scripts": {
     "build": "tsc",
     "dev": "ts-node src/index.ts",
+    "lint": "eslint src",
     "test": "vitest run",
     "test:watch": "vitest"
   },