feat: add ESLint configuration and testing infrastructure

Add comprehensive ESLint setup with React and TypeScript support, create basic integration tests for the shutdown utilities, and enhance the Justfile with a new check command that runs all validation steps (cargo check, clippy, tests, and linting).

web/eslint.config.js

@@ -0,0 +1,63 @@
+import js from '@eslint/js';
+import tseslint from 'typescript-eslint';
+import react from 'eslint-plugin-react';
+import reactHooks from 'eslint-plugin-react-hooks';
+import reactRefresh from 'eslint-plugin-react-refresh';
+
+export default tseslint.config(
+  // Ignore generated files and build outputs
+  {
+    ignores: ['dist', 'node_modules', 'src/routeTree.gen.ts', '*.config.js'],
+  },
+  // Base configs
+  js.configs.recommended,
+  ...tseslint.configs.recommendedTypeChecked,
+  // React plugin configuration
+  {
+    files: ['**/*.{ts,tsx}'],
+    plugins: {
+      react,
+      'react-hooks': reactHooks,
+      'react-refresh': reactRefresh,
+    },
+    languageOptions: {
+      parserOptions: {
+        project: true,
+        tsconfigRootDir: import.meta.dirname,
+        ecmaFeatures: {
+          jsx: true,
+        },
+      },
+    },
+    settings: {
+      react: {
+        version: '19.0',
+      },
+    },
+    rules: {
+      // React rules
+      ...react.configs.recommended.rules,
+      ...react.configs['jsx-runtime'].rules,
+      ...reactHooks.configs.recommended.rules,
+
+      // React Refresh
+      'react-refresh/only-export-components': [
+        'warn',
+        { allowConstantExport: true },
+      ],
+
+      // TypeScript overrides
+      '@typescript-eslint/no-unused-vars': [
+        'error',
+        {
+          argsIgnorePattern: '^_',
+          varsIgnorePattern: '^_',
+        },
+      ],
+      '@typescript-eslint/no-explicit-any': 'warn',
+
+      // Disable prop-types since we're using TypeScript
+      'react/prop-types': 'off',
+    },
+  }
+);