feat: Refactor and modularize flow handling for improved maintainability

- Extracted BuyModeHandler, DesktopFlow, MobileFlow, and SummaryReporter into separate modules for better organization and testability.
- Enhanced type safety and added interfaces for various return types in Load, Logger, UserAgent, and flow modules.
- Implemented comprehensive error handling and logging throughout the new modules.
- Added unit tests for DesktopFlow, MobileFlow, and SummaryReporter to ensure functionality and correctness.
- Updated existing utility functions to support new flow structures and improve code clarity.

src/constants.ts

@@ -30,7 +30,10 @@ export const TIMEOUTS = {
     EXTRA_LONG: 10000,
     DASHBOARD_WAIT: 10000,
     LOGIN_MAX: parseEnvNumber('LOGIN_MAX_WAIT_MS', 180000, 30000, 600000),
-    NETWORK_IDLE: 5000
+    NETWORK_IDLE: 5000,
+    ONE_MINUTE: 60000,
+    ONE_HOUR: 3600000,
+    TWO_MINUTES: 120000
 } as const
 
 export const RETRY_LIMITS = {