259de04f3e
Remove custom SubscriptionManager class and adopt Zustand's built-in selector mechanism for reactive state updates. This simplifies the architecture by eliminating manual subscription management and relying on Zustand's automatic dependency tracking for component re-renders. Key changes: - Remove SubscriptionManager class from store.ts - Replace all notifySubscribers calls with direct store updates - Update hooks to use Zustand selectors with useShallow for complex data - Remove subscribe/unsubscribe patterns from MessageManager - Simplify EmbeddedChat to use selector instead of local state - Rename requestConversationListRefresh to refreshConversations