upgrade eslint (#43)

* chore(eslint): migrate config to flat config and update deps

Migrate ESLint configuration from the legacy `.eslintrc.js` to the new
flat config format in `eslint.config.mjs`. Update ESLint and related
dependencies to latest compatible versions. Adjust rules and plugin
usage to match new config structure. This improves compatibility with
ESLint 9+ and ensures up-to-date linting standards.

* fix: resolve errors after upgrade to ESLint 9.0

Refactor settings and commands modules to use flat exports instead of
namespaces. Update all imports to match the new export style. Remove
the unused protocol.ts file. Improve type safety in requirements and
server modules. This simplifies code structure and aligns with latest
ESLint validation rules.

* chore: enable prettier and fix formatting issues

Fix files to include Prettier formatting.

* chore: add markdown and YAML lint config files

Add .markdownlint.yaml extending Prettier style for markdown linting.
Add .yamllint.yaml extending default rules for YAML linting.

* chore(deps): set min Node.js version to 18.x for builds

- Update Node.js version in CI matrix to 18.x, 20.x, 22.x and set .node-version to 18
- Bump minimum Node.js engine to >=18.20.0 in package-lock.json
- Upgrade major devDependencies: np, eslint, typescript, webpack, boxen, del, configstore, etc.
- Remove deprecated and unused dependencies from lockfile
- Update dependency trees for new versions and drop legacy subdeps
- Improve compatibility with latest Node.js and ecosystem tools

Author: dansomething

.eslintrc.js

@@ -10,12 +10,11 @@ on:
 
 jobs:
   build:
-
     runs-on: ubuntu-latest
 
     strategy:
       matrix:
-        node-version: [16.x, 18.x, 20.x]
+        node-version: [18.x, 20.x, 22.x]
 
     steps:
       - uses: actions/checkout@v3

.github/workflows/node.js.yml

@@ -0,0 +1,2 @@
+---
+extends: 'markdownlint/style/prettier'

.markdownlint.yaml

@@ -0,0 +1 @@
+18

.node-version

@@ -0,0 +1,2 @@
+---
+extends: default

.yamllint.yaml

@@ -17,9 +17,11 @@ An [extension for coc.nvim](https://github.com/neoclide/coc.nvim/wiki/Using-coc-
 
 1. Download and install a recent Java Development Kit (latest Java 8 is the minimum requirement).
 2. Install this extension by running this command in Vim:
-```
-  :CocInstall coc-groovy
-```
+
+   ```sh
+   :CocInstall coc-groovy
+   ```
+
 3. This extension is activated when you first open a Groovy file.
 
 ## Dependencies
@@ -29,8 +31,8 @@ An [extension for coc.nvim](https://github.com/neoclide/coc.nvim/wiki/Using-coc-
 Maven project support requires having the [Maven Wrapper][0] installed in your
 project or having [Maven][1] installed on your environment path.
 
-* [Maven Wrapper][0]
-* [Installing Maven][1]
+- [Maven Wrapper][0]
+- [Installing Maven][1]
 
 ## Available commands
 

Readme.md

@@ -0,0 +1,29 @@
+import tseslint from '@typescript-eslint/eslint-plugin';
+import tsparser from '@typescript-eslint/parser';
+import prettierPlugin from 'eslint-plugin-prettier';
+import prettierConfig from 'eslint-config-prettier';
+
+export default [
+  {
+    files: ['src/**/*.ts'],
+
+    languageOptions: {
+      parser: tsparser,
+      sourceType: 'module',
+    },
+
+    plugins: {
+      '@typescript-eslint': tseslint,
+      prettier: prettierPlugin,
+    },
+
+    rules: {
+      ...tseslint.configs.recommended.rules,
+      ...prettierConfig.rules,
+      '@typescript-eslint/no-unused-vars': 'warn',
+      'no-console': 'warn',
+      semi: ['error', 'always'],
+      'prettier/prettier': 'error',
+    },
+  },
+];