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>

tools/stealth_browser.py

@@ -193,6 +193,47 @@ class StealthBrowser:
                 self.driver = None
                 self._setup_complete = False
 
+    def is_session_valid(self) -> bool:
+        """
+        Check if the browser session is still valid.
+        Returns False if the session has crashed or been closed.
+        """
+        if not self.driver:
+            return False
+
+        try:
+            # Try to get current URL - this will fail if session is invalid
+            _ = self.driver.current_url
+            return True
+        except Exception as e:
+            error_msg = str(e).lower()
+            if "invalid session id" in error_msg or "session deleted" in error_msg or "no such session" in error_msg:
+                logger.warning(f"Browser session invalid: {e}")
+                return False
+            # Other errors might be temporary
+            return True
+
+    def restart(self):
+        """
+        Restart the browser, cleaning up the old session.
+        Useful when the session has become invalid.
+        """
+        logger.info("Restarting stealth browser...")
+
+        # Force cleanup of old driver without trying to save cookies (session is dead)
+        if self.driver:
+            try:
+                self.driver.quit()
+            except Exception:
+                pass  # Ignore errors - session is already dead
+            finally:
+                self.driver = None
+                self._setup_complete = False
+
+        # Start fresh
+        self.start()
+        logger.info("Stealth browser restarted successfully")
+
     def _get_cookie_file(self) -> Path:
         """Get path to cookie file for this session"""
         return SESSION_DIR / f"{self.session_name}_cookies.pkl"