chore: add ESLint, Prettier, Husky + GitHub Actions CI

- ESLint (typescript-eslint) with no-any, no-unused-vars rules
- Prettier (120 width, double quotes, trailing commas)
- Husky pre-commit hook running lint-staged
- GitHub Actions CI: lint → format check → build on push/PR to main
- Add types: ["node"] to tsconfig

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: Albert

.github/workflows/ci.yml

@@ -0,0 +1,29 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  lint-format-build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 20
+          cache: npm
+
+      - run: npm ci
+
+      - name: ESLint
+        run: npm run lint
+
+      - name: Prettier check
+        run: npm run format:check
+
+      - name: TypeScript build
+        run: npm run build

.husky/pre-commit

@@ -0,0 +1 @@
+npx lint-staged

.prettierignore

@@ -0,0 +1,3 @@
+dist/
+node_modules/
+package-lock.json

.prettierrc

@@ -0,0 +1,7 @@
+{
+  "semi": true,
+  "singleQuote": false,
+  "trailingComma": "all",
+  "printWidth": 120,
+  "tabWidth": 2
+}

eslint.config.js

@@ -0,0 +1,16 @@
+import eslint from "@eslint/js";
+import tseslint from "typescript-eslint";
+
+export default tseslint.config(
+  eslint.configs.recommended,
+  ...tseslint.configs.recommended,
+  {
+    ignores: ["dist/", "node_modules/"],
+  },
+  {
+    rules: {
+      "@typescript-eslint/no-unused-vars": ["error", { argsIgnorePattern: "^_" }],
+      "@typescript-eslint/no-explicit-any": "error",
+    },
+  },
+);