Upgrade ESLint to v9 (#443)

* Upgrade eslint to v9. Update configs.

* Add more linting rules. Fix linting errors.

.github/dependabot.yml

@@ -8,10 +8,10 @@ updates:
     labels:
       - "dependencies"
     groups:
-      typescript-eslint:
+      eslint:
         patterns:
-          - "@typescript-eslint/eslint-plugin"
-          - "@typescript-eslint/parser"
+          - "@eslint/js"
+          - "eslint"
     ignore:
       - dependency-name: react
         versions:

ui/eslint.config.js

@@ -0,0 +1,49 @@
+import pluginJs from '@eslint/js';
+import stylisticTs from '@stylistic/eslint-plugin-ts';
+import reactPlugin from 'eslint-plugin-react';
+import tseslint from 'typescript-eslint';
+
+export default [
+  {
+    files: ['**/*.{js,mjs,cjs,ts,jsx,tsx}'],
+    settings: {
+      react: {
+        version: 'detect',
+      },
+    },
+    languageOptions: {
+      parserOptions: {
+        ecmaFeatures: {
+          jsx: true,
+        },
+      },
+    },
+    plugins: {
+      '@stylistic/ts': stylisticTs,
+    },
+  },
+  pluginJs.configs.recommended,
+  ...tseslint.configs.recommended,
+  reactPlugin.configs.flat.recommended,
+  {
+    rules: {
+      // Base Warnings
+      'no-console': 'warn',
+
+      // Stylistic Issues
+      '@stylistic/ts/quotes': ['error', 'single'],
+      '@stylistic/ts/indent': ['error', 2],
+      '@stylistic/ts/semi': ['error', 'always'],
+      '@stylistic/ts/comma-dangle': ['error', 'always-multiline'],
+
+      // TypeScript
+      '@typescript-eslint/no-unused-vars': 'error',
+    },
+  },
+  {
+    rules: {
+      'react/react-in-jsx-scope': 'off',
+    },
+    ignores: ['*.test.tsx'],
+  },
+];