refactor(task-list): enhance task row components with depth handling

- Added depth and maxDepth props to TaskRow, TaskRowWithSubtasks, and TitleColumn components to manage nested subtasks more effectively.
- Updated AddSubtaskRow to support depth for proper indentation and visual hierarchy.
- Improved styling for subtasks based on their depth level, ensuring better visual distinction.
- Adjusted task management slice to utilize actual subtask counts from the backend for accurate display.

worklenz-frontend/src/components/task-list-v2/hooks/useTaskRowColumns.tsx

@@ -58,6 +58,9 @@ interface UseTaskRowColumnsProps {
   // Drag and drop
   attributes: any;
   listeners: any;
+  
+  // Depth for nested subtasks
+  depth?: number;
 }
 
 export const useTaskRowColumns = ({
@@ -84,6 +87,7 @@ export const useTaskRowColumns = ({
   handleTaskNameEdit,
   attributes,
   listeners,
+  depth = 0,
 }: UseTaskRowColumnsProps) => {
   
   const renderColumn = useCallback((columnId: string, width: string, isSticky?: boolean, index?: number) => {
@@ -128,6 +132,7 @@ export const useTaskRowColumns = ({
             onEditTaskName={setEditTaskName}
             onTaskNameChange={setTaskName}
             onTaskNameSave={handleTaskNameSave}
+            depth={depth}
           />
         );