chore: enhance development environment

- Add .editorconfig for unified editor settings
- Add .nvmrc to specify Node.js version (20)
- Add useful npm scripts: format, format:check, lint, lint:fix, type-check

package.json

@@ -8,6 +8,11 @@
   "type": "module",
   "scripts": {
     "clean": "npx prettier . --write",
+    "format": "prettier --write .",
+    "format:check": "prettier --check .",
+    "lint": "eslint .",
+    "lint:fix": "eslint --fix .",
+    "type-check": "tsc --noEmit",
     "dev": "vite",
     "build": "vite build && tsc -p tsconfig.node.json",
     "build:backend": "tsc -p tsconfig.node.json",