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/components/StepIndicator.tsx

@@ -6,7 +6,11 @@ interface StepIndicatorProps {
   steps?: string[]
 }
 
-export function StepIndicator({ currentStep, onStepClick, steps = DEFAULT_STEPS }: StepIndicatorProps) {
+export function StepIndicator({
+  currentStep,
+  onStepClick,
+  steps = DEFAULT_STEPS,
+}: StepIndicatorProps) {
   return (
     <nav aria-label="Progress" className="mb-8">
       <ol className="flex items-center">