feat: add ESLint with TypeScript/React plugins and fix all lint errors

- Add ESLint 9 configuration (eslint.config.mjs) with TypeScript and React hooks plugins
- Add npm run lint:eslint command for code quality checks
- Expand npm run lint to check all three TypeScript configs (renderer, main, cli)
- Update tsconfig.cli.json to include src/prompts and src/types directories

Fix 29 ESLint errors:
- Remove unused updateCliActivity import in batch-processor.ts
- Convert {false && <jsx>} patterns to comments in AutoRun components
- Wrap case block with const declarations in braces (AgentSelectionScreen)
- Fix unused expression pattern in PreparingPlanScreen
- Fix conditional hook calls in FilePreview, OfflineQueueBanner, RecentCommandChips, TerminalOutput
- Add windows-diagnostics.json to PackageContents interface

Update CLAUDE.md and CONTRIBUTING.md with new linting commands and documentation.

Claude ID: 029e8abe-5734-4967-9fb4-c85078c1973d
Maestro ID: 87ffa06e-0ecd-4eb8-b327-dad1ec24f7a9

eslint.config.mjs

@@ -0,0 +1,86 @@
+// @ts-check
+import eslint from '@eslint/js';
+import tseslint from 'typescript-eslint';
+import reactPlugin from 'eslint-plugin-react';
+import reactHooksPlugin from 'eslint-plugin-react-hooks';
+import globals from 'globals';
+
+export default tseslint.config(
+  // Ignore patterns
+  {
+    ignores: [
+      'dist/**',
+      'release/**',
+      'node_modules/**',
+      '*.config.js',
+      '*.config.mjs',
+      '*.config.ts',
+      'scripts/**',
+      'src/__tests__/**',
+      'src/web/utils/serviceWorker.ts', // Service worker has special globals
+      'src/web/public/**', // Service worker and static assets
+    ],
+  },
+
+  // Base ESLint recommended rules
+  eslint.configs.recommended,
+
+  // TypeScript ESLint recommended rules
+  ...tseslint.configs.recommended,
+
+  // Main configuration for all TypeScript files
+  {
+    files: ['src/**/*.ts', 'src/**/*.tsx'],
+    languageOptions: {
+      ecmaVersion: 2020,
+      sourceType: 'module',
+      globals: {
+        ...globals.browser,
+        ...globals.node,
+        ...globals.es2020,
+      },
+      parserOptions: {
+        ecmaFeatures: {
+          jsx: true,
+        },
+      },
+    },
+    plugins: {
+      react: reactPlugin,
+      'react-hooks': reactHooksPlugin,
+    },
+    rules: {
+      // TypeScript-specific rules
+      '@typescript-eslint/no-unused-vars': ['warn', {
+        argsIgnorePattern: '^_',
+        varsIgnorePattern: '^_',
+      }],
+      '@typescript-eslint/no-explicit-any': 'off', // Too many existing uses
+      '@typescript-eslint/no-empty-object-type': 'off',
+      '@typescript-eslint/no-require-imports': 'off', // Used in main process
+
+      // React rules
+      'react/jsx-uses-react': 'error',
+      'react/jsx-uses-vars': 'error',
+      'react/prop-types': 'off', // Using TypeScript for prop types
+      'react/react-in-jsx-scope': 'off', // Not needed with new JSX transform
+
+      // React Hooks rules
+      'react-hooks/rules-of-hooks': 'error',
+      'react-hooks/exhaustive-deps': 'warn',
+
+      // General rules
+      'no-console': 'off', // Console is used throughout
+      'no-undef': 'off', // TypeScript handles this
+      'no-control-regex': 'off', // Intentionally used for terminal escape sequences
+      'no-useless-escape': 'off', // Sometimes needed for clarity in regexes
+      'prefer-const': 'warn',
+      'no-var': 'error',
+    },
+    settings: {
+      react: {
+        version: 'detect',
+      },
+    },
+  },
+);