Add Rate Monitor app — Booking.com + direct booking engine competitor rates

Combines Booking.com Playwright scraper (from forecasting), direct booking
engine scraper (ported from laptop-archive/guestline-monitor), and Newbook
own-hotel rates into one focused tool. Four views: Bookability, Market View
(with price index badges + direct rate sub-rows), Direct Rates (per-competitor
room breakdown, min-stay flags, hotel config/discovery), Rate Analysis
(advance purchase curve, DOW chart, rate timeline, comparison table).

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

backend/services/scraper_backends/__init__.py

@@ -0,0 +1,20 @@
+"""
+Scraper backends for booking.com rate scraping.
+
+Provides pluggable backends to allow switching between:
+- playwright_local: Direct Playwright (default)
+- playwright_proxy: Playwright with rotating proxies (future)
+- apify_backend: Apify scraping service (future)
+"""
+
+from .base import ScraperBackend, ScraperResult, HotelData, RateData, AvailabilityStatus
+from .playwright_local import PlaywrightLocalBackend
+
+__all__ = [
+    'ScraperBackend',
+    'ScraperResult',
+    'HotelData',
+    'RateData',
+    'AvailabilityStatus',
+    'PlaywrightLocalBackend',
+]