Update loaders, handlers, and BotClient to use centralized logger:
- CommandLoader.ts and EventLoader.ts
- AutocompleteHandler.ts, CommandHandler.ts, ComponentInteractionHandler.ts
- BotClient.ts
Provides consistent formatting across all core library logging.
- Delegate command loading to CommandLoader
- Delegate event loading to EventLoader
- Remove readCommandsRecursively and readEventsRecursively methods
- Remove isValidCommand and isValidEvent methods (moved to loaders)
- Add summary logging with load statistics
- Export Client class for better type safety
- Reduce file from 188 to 97 lines (48% reduction)
BREAKING CHANGE: Client class is now exported as a named export
