Browser session recovery, price tracking, and dashboard improvements

- Add browser session validation and auto-restart for BestBuy/GameStop scrapers
- Add price change detection and notifications
- Remove PokemonCenter scraper (now uses Chrome Extension)
- Dashboard UI improvements

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

scrapers/__init__.py

@@ -1,12 +1,11 @@
 # Scrapers package
-from .pokemoncenter import PokemonCenterScraper
+# Note: Pokemon Center uses Chrome Extension (chrome-extension/), not a Python scraper
 from .target import TargetScraper
 from .gamestop import GameStopScraper, warmup_gamestop
 from .bestbuy import BestBuyScraper
 from .walmart import WalmartScraper
 
 __all__ = [
-    "PokemonCenterScraper",
     "TargetScraper",
     "GameStopScraper",
     "BestBuyScraper",