Add pre-commit hooks for linting and formatting

Set up pre-commit framework with ruff (backend) and ESLint/Prettier/tsc
(frontend) hooks to catch issues locally before CI. Auto-format all
frontend files with Prettier to comply with the new check.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/pages/Home.tsx

@@ -5,8 +5,7 @@ import type { RunStatus } from '../types'
 const statusStyles: Record<RunStatus, string> = {
   active:
     'bg-green-100 text-green-800 dark:bg-green-900/40 dark:text-green-300',
-  completed:
-    'bg-blue-100 text-blue-800 dark:bg-blue-900/40 dark:text-blue-300',
+  completed: 'bg-blue-100 text-blue-800 dark:bg-blue-900/40 dark:text-blue-300',
   failed: 'bg-red-100 text-red-800 dark:bg-red-900/40 dark:text-red-300',
 }