feat(task-management): enhance Checkbox component and task selection functionality

- Added `indeterminate` state to Checkbox component for better visual representation of partial selections.
- Updated TaskGroup and VirtualizedTaskList components to utilize the new Checkbox features, allowing for group selection with indeterminate states.
- Implemented custom debounce function for saving task fields to localStorage, improving performance during user interactions.
- Enhanced task row styling for better visibility and user experience, particularly in dark mode.

worklenz-frontend/src/components/Checkbox.tsx

@@ -6,6 +6,7 @@ interface CheckboxProps {
   isDarkMode?: boolean;
   className?: string;
   disabled?: boolean;
+  indeterminate?: boolean;
 }
 
 const Checkbox: React.FC<CheckboxProps> = ({ 
@@ -13,7 +14,8 @@ const Checkbox: React.FC<CheckboxProps> = ({
   onChange, 
   isDarkMode = false, 
   className = '',
-  disabled = false 
+  disabled = false,
+  indeterminate = false
 }) => {
   return (
     <label className={`inline-flex items-center cursor-pointer ${disabled ? 'opacity-50 cursor-not-allowed' : ''} ${className}`}>
@@ -25,15 +27,20 @@ const Checkbox: React.FC<CheckboxProps> = ({
         className="sr-only"
       />
       <div className={`w-4 h-4 border-2 rounded transition-all duration-200 flex items-center justify-center ${
-        checked 
+        checked || indeterminate
           ? `${isDarkMode ? 'bg-blue-600 border-blue-600' : 'bg-blue-500 border-blue-500'}` 
           : `${isDarkMode ? 'bg-gray-800 border-gray-600 hover:border-gray-500' : 'bg-white border-gray-300 hover:border-gray-400'}`
       } ${disabled ? 'cursor-not-allowed' : ''}`}>
-        {checked && (
+        {checked && !indeterminate && (
           <svg className="w-3 h-3 text-white" fill="currentColor" viewBox="0 0 20 20">
             <path fillRule="evenodd" d="M16.707 5.293a1 1 0 010 1.414l-8 8a1 1 0 01-1.414 0l-4-4a1 1 0 011.414-1.414L8 12.586l7.293-7.293a1 1 0 011.414 0z" clipRule="evenodd" />
           </svg>
         )}
+        {indeterminate && (
+          <svg className="w-3 h-3 text-white" fill="currentColor" viewBox="0 0 20 20">
+            <path fillRule="evenodd" d="M3 10a1 1 0 011-1h12a1 1 0 110 2H4a1 1 0 01-1-1z" clipRule="evenodd" />
+          </svg>
+        )}
       </div>
     </label>
   );