chore: 添加 iOS/Android 相机和相册权限配置

apps/lib/features/calendar/ui/widgets/create_event_sheet.dart

@@ -113,8 +113,13 @@ class _CreateEventSheetState extends State<CreateEventSheet>
   }
 
   DateTime _roundToNearestMinute(DateTime dt, int interval) {
-    final minute = (dt.minute / interval).round() * interval;
-    return DateTime(dt.year, dt.month, dt.day, dt.hour, minute % 60);
+    final totalMinutes = dt.hour * 60 + dt.minute;
+    final rounded = ((totalMinutes / interval).round() * interval);
+    final hours = rounded ~/ 60;
+    final minutes = rounded % 60;
+    final dayOffset = hours >= 24 ? 1 : 0;
+    final newHour = hours % 24;
+    return DateTime(dt.year, dt.month, dt.day + dayOffset, newHour, minutes);
   }
 
   @override
@@ -242,8 +247,27 @@ class _CreateEventSheetState extends State<CreateEventSheet>
             _endTime ?? _startTime,
             (date, time) {
               setState(() {
-                _endDate = date;
-                _endTime = time;
+                final startDateTime = DateTime(
+                  _startDate.year,
+                  _startDate.month,
+                  _startDate.day,
+                  _startTime.hour,
+                  _startTime.minute,
+                );
+                final endDateTime = DateTime(
+                  date.year,
+                  date.month,
+                  date.day,
+                  time.hour,
+                  time.minute,
+                );
+                if (endDateTime.isBefore(startDateTime)) {
+                  _endDate = _startDate;
+                  _endTime = _startTime;
+                } else {
+                  _endDate = date;
+                  _endTime = time;
+                }
               });
             },
             isOptional: true,