fix: Add validation to prevent target exceeding pending tasks in assign task functionality

lib/model/dailyTaskPlaning/assign_task_bottom_sheet .dart

@@ -381,6 +381,16 @@ class _AssignTaskBottomSheetState extends State<AssignTaskBottomSheet> {
       return;
     }
 
+    if (target > widget.pendingTask) {
+      showAppSnackbar(
+        title: "Target Too High",
+        message:
+            "Target cannot be greater than pending task (${widget.pendingTask})",
+        type: SnackbarType.error,
+      );
+      return;
+    }
+
     final description = descriptionController.text.trim();
     if (description.isEmpty) {
       showAppSnackbar(