feat: add terminal panel components and Zustand store for state management

- Created a barrel export file for terminal panel components.
- Implemented Zustand store for managing terminal panel UI state, including visibility, active terminal, view mode, and terminal ordering.
- Added actions for opening/closing the terminal panel, setting the active terminal, changing view modes, and managing terminal order.
- Introduced selectors for accessing terminal panel state properties.

ccw/frontend/src/hooks/useSessions.ts

@@ -168,7 +168,7 @@ export function useCreateSession(): UseCreateSessionReturn {
 
   const mutation = useMutation({
     mutationFn: createSession,
-    onSuccess: (newSession) => {
+    onSuccess: () => {
       // Invalidate sessions cache to trigger refetch
       queryClient.invalidateQueries({ queryKey: ['workspace'] });
       // Invalidate dashboard stats