Convert to use typescript, implement eslint

eslint.config.js

@@ -0,0 +1,41 @@
+const eslint = require('@eslint/js');
+const tseslint = require('typescript-eslint');
+
+module.exports = tseslint.config(
+  eslint.configs.recommended,
+  ...tseslint.configs.recommendedTypeChecked,
+  {
+    languageOptions: {
+      parserOptions: {
+        projectService: true,
+        tsconfigRootDir: __dirname,
+      },
+    },
+    rules: {
+      '@typescript-eslint/no-unused-vars': ['error', { argsIgnorePattern: '^_' }],
+      '@typescript-eslint/prefer-readonly': 'error',
+      '@typescript-eslint/no-unnecessary-type-assertion': 'error',
+      '@typescript-eslint/no-useless-constructor': 'error',
+      '@typescript-eslint/prefer-optional-chain': 'error',
+      '@typescript-eslint/prefer-nullish-coalescing': 'error',
+      '@typescript-eslint/no-require-imports': 'off',
+      '@typescript-eslint/no-non-null-assertion': 'off',
+      '@typescript-eslint/no-misused-promises': ['error', { checksVoidReturn: false }],
+      '@typescript-eslint/restrict-template-expressions': ['error', { allowNumber: true }],
+      'no-useless-return': 'error',
+      'no-var': 'error',
+      'prefer-const': 'error',
+      'no-console': 'off',
+    },
+  },
+  {
+    files: ['src/renderer.ts'],
+    rules: {
+      '@typescript-eslint/no-unsafe-assignment': 'off',
+      '@typescript-eslint/no-unsafe-member-access': 'off',
+    },
+  },
+  {
+    ignores: ['build/', 'dist/', 'node_modules/', 'assets/'],
+  }
+);