Add booking flow, business hours, and dark mode support

Features:
- Complete multi-step booking flow with service selection, date/time picker,
  auth (login/signup with email verification), payment, and confirmation
- Business hours settings page for defining when business is open
- TimeBlock purpose field (BUSINESS_HOURS, CLOSURE, UNAVAILABLE)
- Service resource assignment with prep/takedown time buffers
- Availability checking respects business hours and service buffers
- Customer registration via email verification code

UI/UX:
- Full dark mode support for all booking components
- Separate first/last name fields in signup form
- Back buttons on each wizard step
- Removed auto-redirect from confirmation page

API:
- Public endpoints for services, availability, business hours
- Customer verification and registration endpoints
- Tenant lookup from X-Business-Subdomain header

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/tailwind.config.js

@@ -1,5 +1,6 @@
 /** @type {import('tailwindcss').Config} */
 export default {
+    darkMode: 'media', // Follow browser's color scheme preference
     content: [
         "./index.html",
         "./src/**/*.{js,ts,jsx,tsx}",