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

package.json

@@ -33,7 +33,8 @@
     "start": "electron .",
     "clean": "rm -rf dist release node_modules/.vite",
     "postinstall": "electron-rebuild -f -w node-pty",
-    "lint": "tsc -p tsconfig.lint.json",
+    "lint": "tsc -p tsconfig.lint.json && tsc -p tsconfig.main.json --noEmit && tsc -p tsconfig.cli.json --noEmit",
+    "lint:eslint": "eslint src/",
     "test": "vitest run",
     "test:watch": "vitest",
     "test:coverage": "vitest run --coverage",
@@ -222,6 +223,7 @@
   },
   "devDependencies": {
     "@electron/notarize": "^3.1.1",
+    "@eslint/js": "^9.39.2",
     "@playwright/test": "^1.57.0",
     "@testing-library/jest-dom": "^6.9.1",
     "@testing-library/react": "^16.3.0",
@@ -234,6 +236,8 @@
     "@types/react-dom": "^18.2.18",
     "@types/react-syntax-highlighter": "^15.5.13",
     "@types/ws": "^8.5.10",
+    "@typescript-eslint/eslint-plugin": "^8.50.1",
+    "@typescript-eslint/parser": "^8.50.1",
     "@vitejs/plugin-react": "^4.2.1",
     "@vitest/coverage-v8": "^4.0.15",
     "autoprefixer": "^10.4.16",
@@ -244,6 +248,10 @@
     "electron-playwright-helpers": "^2.0.1",
     "electron-rebuild": "^3.2.9",
     "esbuild": "^0.24.2",
+    "eslint": "^9.39.2",
+    "eslint-plugin-react": "^7.37.5",
+    "eslint-plugin-react-hooks": "^7.0.1",
+    "globals": "^16.5.0",
     "jsdom": "^27.2.0",
     "lucide-react": "^0.303.0",
     "playwright": "^1.57.0",
@@ -252,6 +260,7 @@
     "react-dom": "^18.2.0",
     "tailwindcss": "^3.4.1",
     "typescript": "^5.3.3",
+    "typescript-eslint": "^8.50.1",
     "vite": "^5.0.11",
     "vite-plugin-electron": "^0.28.2",
     "vitest": "^4.0.15"