Feat: Added time remaining(deadline countdown) calculation for Date Cells

frontend/appflowy_flutter/lib/plugins/database/widgets/cell/card_cell_skeleton/date_card_cell.dart

@@ -1,8 +1,8 @@
 import 'package:appflowy/generated/flowy_svgs.g.dart';
+import 'package:appflowy/plugins/database/application/cell/bloc/date_cell_bloc.dart';
 import 'package:appflowy/plugins/database/application/cell/cell_controller.dart';
 import 'package:appflowy/plugins/database/application/cell/cell_controller_builder.dart';
 import 'package:appflowy/plugins/database/application/database_controller.dart';
-import 'package:appflowy/plugins/database/application/cell/bloc/date_cell_bloc.dart';
 import 'package:flowy_infra_ui/flowy_infra_ui.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_bloc/flutter_bloc.dart';
@@ -57,6 +57,10 @@ class _DateCellState extends State<DateCardCell> {
             return const SizedBox.shrink();
           }
 
+          final timeRemaining = getTimeRemainingFromCellData(state.cellData);
+          final isOverdue = state.cellData.dateTime != null &&
+              state.cellData.dateTime!.isBefore(DateTime.now());
+
           return Container(
             alignment: Alignment.centerLeft,
             padding: widget.style.padding,
@@ -73,6 +77,19 @@ class _DateCellState extends State<DateCardCell> {
                   const HSpace(4),
                   const FlowySvg(FlowySvgs.clock_alarm_s),
                 ],
+                if (timeRemaining.isNotEmpty) ...[
+                  const HSpace(8),
+                  Text(
+                    timeRemaining,
+                    style: widget.style.textStyle.copyWith(
+                      fontSize: 11,
+                      color: isOverdue
+                          ? Colors.red.shade600
+                          : (widget.style.textStyle.color ?? Colors.grey)
+                              .withValues(alpha: 0.6),
+                    ),
+                  ),
+                ],
               ],
             ),
           );

frontend/appflowy_flutter/lib/plugins/database/widgets/cell/editable_cell_skeleton/date.dart

@@ -122,6 +122,40 @@ String getDateCellStrFromCellData(FieldInfo field, DateCellData cellData) {
   }
 }
 
+/// Returns a human-readable string representing the time remaining until the given date
+/// or how long overdue it is
+/// e.g., "3 days left", "2 hours left", "5 minutes left" (for future dates)
+///       "2 days overdue", "3 hours overdue" (for past dates)
+/// Returns an empty string if cellData.dateTime is null
+String getTimeRemainingFromCellData(DateCellData cellData) {
+  if (cellData.dateTime == null) {
+    return "";
+  }
+
+  final now = DateTime.now();
+  final targetDate = cellData.dateTime!;
+  final difference = targetDate.difference(now);
+
+  // Calculate absolute time difference
+  final absDifference = difference.abs();
+  final days = absDifference.inDays;
+  final hours = absDifference.inHours;
+  final minutes = absDifference.inMinutes;
+
+  // Determine if it's overdue or upcoming
+  final isOverdue = difference.isNegative;
+
+  if (days > 0) {
+    return "$days day${days == 1 ? '' : 's'} ${isOverdue ? 'overdue' : 'left'}";
+  } else if (hours > 0) {
+    return "$hours hour${hours == 1 ? '' : 's'} ${isOverdue ? 'overdue' : 'left'}";
+  } else if (minutes > 0) {
+    return "$minutes min${minutes == 1 ? '' : 's'} ${isOverdue ? 'overdue' : 'left'}";
+  } else {
+    return isOverdue ? "Overdue" : "Less than a minute";
+  }
+}
+
 extension GetDateFormatExtension on DateFormatPB {
   String get pattern => switch (this) {
         DateFormatPB.Local => 'MM/dd/y',