feat: enhance date handling in TaskBasicFields and date-utils

- Integrated `ensureDate` and `formatDateForDateTimeInput` in `TaskBasicFields` for improved due date management.
- Updated `date-utils` functions to accept both `Date` and `string` types, ensuring robust date validation and parsing.
- Added `ensureDate` utility to handle various date inputs, improving error handling and consistency across date-related functions.

src/components/forms/task/TaskBasicFields.tsx

@@ -3,6 +3,7 @@
 import { Input } from '@/components/ui/Input';
 import { TaskPriority, TaskStatus } from '@/lib/types';
 import { getAllStatuses, getAllPriorities } from '@/lib/status-config';
+import { ensureDate, formatDateForDateTimeInput } from '@/lib/date-utils';
 
 interface TaskBasicFieldsProps {
   title: string;
@@ -109,7 +110,10 @@ export function TaskBasicFields({
       <Input
         label="Date d'échéance"
         type="datetime-local"
-        value={dueDate ? new Date(dueDate.getTime() - dueDate.getTimezoneOffset() * 60000).toISOString().slice(0, 16) : ''}
+        value={(() => {
+          const date = ensureDate(dueDate);
+          return date ? formatDateForDateTimeInput(date) : '';
+        })()}
         onChange={(e) => onDueDateChange(e.target.value ? new Date(e.target.value) : undefined)}
         disabled={loading}
       />