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',
+    },
+  }
+);

web/package.json

@@ -7,7 +7,8 @@
     "start": "vite --port 3000",
     "build": "vite build && tsc",
     "serve": "vite preview",
-    "test": "vitest run"
+    "test": "vitest run",
+    "lint": "tsc && eslint . --ext .ts,.tsx"
   },
   "dependencies": {
     "@radix-ui/themes": "^3.2.1",
@@ -23,14 +24,20 @@
     "recharts": "^3.2.0"
   },
   "devDependencies": {
+    "@eslint/js": "^9.39.0",
     "@testing-library/dom": "^10.4.0",
     "@testing-library/react": "^16.2.0",
     "@types/node": "^24.3.3",
     "@types/react": "^19.0.8",
     "@types/react-dom": "^19.0.3",
     "@vitejs/plugin-react": "^4.3.4",
+    "eslint": "^9.39.0",
+    "eslint-plugin-react": "^7.37.5",
+    "eslint-plugin-react-hooks": "^7.0.1",
+    "eslint-plugin-react-refresh": "^0.4.24",
     "jsdom": "^26.0.0",
     "typescript": "^5.7.2",
+    "typescript-eslint": "^8.46.2",
     "vite": "^6.3.5",
     "vitest": "^3.0.5",
     "web-vitals": "^4.2.4"

web/src/lib/api.ts

@@ -43,7 +43,7 @@ export class BannerApiClient {
       );
     }
 
-    return response.json();
+    return (await response.json()) as T;
   }
 
   async getHealth(): Promise<HealthResponse> {

web/src/reportWebVitals.ts

@@ -1,6 +1,6 @@
 const reportWebVitals = (onPerfEntry?: () => void) => {
   if (onPerfEntry && onPerfEntry instanceof Function) {
-    import('web-vitals').then(({ onCLS, onINP, onFCP, onLCP, onTTFB }) => {
+    void import('web-vitals').then(({ onCLS, onINP, onFCP, onLCP, onTTFB }) => {
       onCLS(onPerfEntry)
       onINP(onPerfEntry)
       onFCP(onPerfEntry)

web/src/routes/index.tsx

@@ -237,11 +237,11 @@ function App() {
       }
 
       // Schedule the next request after the current one completes
-      timeoutId = setTimeout(fetchData, REFRESH_INTERVAL);
+      timeoutId = setTimeout(() => void fetchData(), REFRESH_INTERVAL);
     };
 
     // Start the first request immediately
-    fetchData();
+    void fetchData();
 
     return () => {
       if (timeoutId) {

web/tsconfig.json

@@ -11,6 +11,7 @@
     "moduleResolution": "bundler",
     "allowImportingTsExtensions": true,
     "verbatimModuleSyntax": true,
+    "isolatedModules": true,
     "noEmit": true,
 
     /* Linting */