chore: Update package dependencies and ESLint configuration in backen…

.github/workflows/lint.yml

@@ -0,0 +1,38 @@
+name: Lint
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  lint-backend:
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: backend
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: '20'
+          cache: npm
+          cache-dependency-path: backend/package-lock.json
+      - run: npm ci
+      - run: npx eslint src --ext .ts --max-warnings 0
+
+  lint-client:
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: client
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: '20'
+          cache: npm
+          cache-dependency-path: client/package-lock.json
+      - run: npm ci
+      - run: npx next lint

.gitignore

@@ -100,4 +100,4 @@ coverage/
 *.claude
 CLAUDE.md
 
-backend/package-lock.json
+!backend/package-lock.json

backend/.eslintrc.cjs

@@ -0,0 +1,24 @@
+module.exports = {
+  root: true,
+  env: {
+    node: true,
+    es2022: true,
+    jest: true,
+  },
+  parser: "@typescript-eslint/parser",
+  parserOptions: {
+    project: "./tsconfig.json",
+    tsconfigRootDir: __dirname,
+  },
+  plugins: ["@typescript-eslint"],
+  extends: [
+    "eslint:recommended",
+    "plugin:@typescript-eslint/recommended",
+  ],
+  rules: {
+    "@typescript-eslint/no-explicit-any": "error",
+    "@typescript-eslint/no-floating-promises": "error",
+    "no-console": "warn",
+    "@typescript-eslint/no-unused-vars": "error",
+  },
+};